Onclick event; If and Else

Onclick event; If and Else - javascript

All right so I am doing a javascript code for a login type form and it will lead you to a new page. Here it is:
function submit1()
{
var x=document.getElementById("username");
var y=document.getElementById("password");
if (x.value=="username" && y.value=="password")
{
window.location="Example.php";
}
else
{
window.alert=("The information you have submitted is incorrect and needs to be submitted again!");
}
}
When ever I am hitting the submit button it takes me straight to the page instead of checking to see if it right. Please help!
Thank you in advanced! To let you know this is not a permanet login page!

The easy way to do this would be to use a button input:
<input type="button" value="Check" onclick = "submit1();" />
The alternative is to prevent this default behavior of a submit type input, by making the handler return false. Your HTML would look like this:
<input type="submit" value="Check" onclick = "return submit1();" />
Your function would need to be changed a well (considering the fact that you want it to not redirect). I am assuming you want to preserve data entered, so I am not going to use window.location to redirect. Instead, I am going to allow the form to be submitted:
function submit1()
{
var x=document.getElementById("username");
var y=document.getElementById("password");
if (x.value == "username" && y.value == "password") {
window.alert=("The information you have submitted is incorrect and needs to be submitted again!");
return false;
}
}

<html>
<head>
<title>
Login page
</title>
</head>
<body>
<h1 style="font-family:Comic Sans Ms;text-align="center";font-size:20pt;
color:#00FF00;>
Simple Login Page
</h1>
<form name="login">
Username<input type="text" name="userid"/>
Password<input type="password" name="pswrd"/>
<input type="button" onclick="check(this.form)" value="Login"/>
<input type="reset" value="Cancel"/>
</form>
<script language="javascript">
function check(form)/*function to check userid & password*/
{
/*the following code checkes whether the entered userid and password are matching*/
if(form.userid.value == "myuserid" && form.pswrd.value == "mypswrd")
{
window.location="Example.php"; /*opens the target page while Id & password matches*/
}
else
{
alert("Error Password or Username")/*displays error message*/
}
}
</script>
</body>
</html>

The event needs to cancel the default event and return false. This will prevent the form from submitting.
HOWEVER, it should be a non-issue if the form submits anyway, because JavaScript CANNOT be trusted and therefore you MUST validate all input server-side.

<form method="post" action="." id="myform">
<!-- form contents --->
</form>
<script type="text/javascript">
(function () {
var f = document.getElementById('myform'), // get your form element
x = document.getElementById('username'),
y = document.getElementById('password'),
handler;
handler = function (e) {
e.preventDefault(); // stop submit
if (x.value=='username' && y.value=='password') {
window.location = 'Example.php';
} else {
window.alert('The information...');
}
};
// listen to submit event
if ('addEventListener' in f) {
f.addEventListener('submit', handler, false);
} else { // handle also IE...
f.attachEvent('submit', function () {
handler(window.event);
});
}
}());
</script>
anyway it looks like you're trying to check login/password from JS what is not greatest idea (anyone can just look into source and read it)

Related

Reload the document to reset the game when it running [duplicate]

How would I go about preventing the page from refreshing when pressing the send button without any data in the fields?
The validation is setup working fine, all fields go red but then the page is immediately refreshed. My knowledge of JS is relatively basic.
In particular I think the processForm() function at the bottom is 'bad'.
HTML
<form id="prospects_form" method="post">
<input id="form_name" tabindex="1" class="boxsize" type="text" name="name" placeholder="Full name*" maxlength="80" value="" />
<input id="form_email" tabindex="2" class="boxsize" type="text" name="email" placeholder="Email*" maxlength="100" value="" />
<input id="form_subject" class="boxsize" type="text" name="subject" placeholder="Subject*" maxlength="50" value="FORM: Row for OUBC" />
<textarea id="form_message" class="boxsize" name="message" placeholder="Message*" tabindex="3" rows="6" cols="5" maxlength="500"></textarea>
<button id="form_send" tabindex="5" class="btn" type="submit" onclick="return processForm()">Send</button>
<div id="form_validation">
<span class="form_captcha_code"></span>
<input id="form_captcha" class="boxsize" type="text" name="form_captcha" placeholder="Enter code" tabindex="4" value="" />
</div>
<div class="clearfix"></div>
</form>
JS
$(document).ready(function() {
// Add active class to inputs
$("#prospects_form .boxsize").focus(function() { $(this).addClass("hasText"); });
$("#form_validation .boxsize").focus(function() { $(this).parent().addClass("hasText"); });
// Remove active class from inputs (if empty)
$("#prospects_form .boxsize").blur(function() { if ( this.value === "") { $(this).removeClass("hasText"); } });
$("#form_validation .boxsize").blur(function() { if ( this.value === "") { $(this).parent().removeClass("hasText"); } });
///////////////////
// START VALIDATION
$("#prospects_form").ready(function() {
// DEFINE GLOBAL VARIABLES
var valName = $('#form_name'),
valEmail = $("#form_email"),
valEmailFormat = /^(([^<>()[\]\\.,;:\s#\"]+(\.[^<>()[\]\\.,;:\s#\"]+)*)|(\".+\"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/,
valMsg = $('#form_message'),
valCaptcha = $('#form_captcha'),
valCaptchaCode = $('.form_captcha_code');
// Generate captcha
function randomgen() {
var rannumber = "";
// Iterate through 1 to 9, 4 times
for(ranNum=1; ranNum<=4; ranNum++){ rannumber+=Math.floor(Math.random()*10).toString(); }
// Apply captcha to element
valCaptchaCode.html(rannumber);
}
randomgen();
// CAPTCHA VALIDATION
valCaptcha.blur(function() {
function formCaptcha() {
if ( valCaptcha.val() == valCaptchaCode.html() ) {
// Incorrect
valCaptcha.parent().addClass("invalid");
return false;
} else {
// Correct
valCaptcha.parent().removeClass("invalid");
return true;
}
}
formCaptcha();
});
// Remove invalid class from captcha if typing
valCaptcha.keypress(function() {
valCaptcha.parent().removeClass("invalid");
});
// EMAIL VALIDATION (BLUR)
valEmail.blur(function() {
function formEmail() {
if (!valEmailFormat.test(valEmail.val()) && valEmail.val() !== "" ) {
// Incorrect
valEmail.addClass("invalid");
} else {
// Correct
valEmail.removeClass("invalid");
}
}
formEmail();
});
// Remove invalid class from email if typing
valEmail.keypress(function() {
valEmail.removeClass("invalid");
});
// VALIDATION ON SUBMIT
$('#prospects_form').submit(function() {
console.log('user hit send button');
// EMAIL VALIDATION (SUBMIT)
function formEmailSubmit() {
if (!valEmailFormat.test(valEmail.val())) {
// Incorrect
valEmail.addClass("invalid");
} else {
// Correct
valEmail.removeClass("invalid");
}
}
formEmailSubmit();
// Validate captcha
function formCaptchaSubmit() {
if( valCaptcha.val() === valCaptchaCode.html() ) {
// Captcha is correct
} else {
// Captcha is incorrect
valCaptcha.parent().addClass("invalid");
randomgen();
}
}
formCaptchaSubmit();
// If NAME field is empty
function formNameSubmit() {
if ( valName.val() === "" ) {
// Name is empty
valName.addClass("invalid");
} else {
valName.removeClass("invalid");
}
}
formNameSubmit();
// If MESSAGE field is empty
function formMessageSubmit() {
if ( valMsg.val() === "" ) {
// Name is empty
valMsg.addClass("invalid");
} else {
valMsg.removeClass("invalid");
}
}
formMessageSubmit();
// Submit form (if all good)
function processForm() {
if ( formEmailSubmit() && formCaptchaSubmit() && formNameSubmit() && formMessageSubmit() ) {
$("#prospects_form").attr("action", "/clients/oubc/row-for-oubc-send.php");
$("#form_send").attr("type", "submit");
return true;
} else if( !formEmailSubmit() ) {
valEmail.addClass("invalid");
return false;
} else if ( !formCaptchaSubmit() ) {
valCaptcha.parent().addClass("invalid");
return false;
} else if ( !formNameSubmit() ) {
valName.addClass("invalid");
return false;
} else if ( !formMessageSubmit() ) {
valMsg.addClass("invalid");
return false;
} else {
return false;
}
}
});
});
// END VALIDATION
/////////////////
});

You can prevent the form from submitting with
$("#prospects_form").submit(function(e) {
e.preventDefault();
});
Of course, in the function, you can check for empty fields, and if anything doesn't look right, e.preventDefault() will stop the submit.
Without jQuery:
var form = document.getElementById("myForm");
function handleForm(event) { event.preventDefault(); }
form.addEventListener('submit', handleForm);

Add this onsubmit="return false" code:
<form onsubmit="return false">
That fixed it for me. It will still run the onClick function you specify.

Replace button type to button:
<button type="button">My Cool Button</button>

One great way to prevent reloading the page when submitting using a form is by adding return false with your onsubmit attribute.
<form onsubmit="yourJsFunction();return false">
<input type="text"/>
<input type="submit"/>
</form>

You can use this code for form submission without a page refresh. I have done this in my project.
$(function () {
$('#myFormName').on('submit',function (e) {
$.ajax({
type: 'post',
url: 'myPageName.php',
data: $('#myFormName').serialize(),
success: function () {
alert("Email has been sent!");
}
});
e.preventDefault();
});
});

This problem becomes more complex when you give the user 2 possibilities to submit the form:
by clicking on an ad hoc button
by hitting Enter key
In such a case you will need a function which detects the pressed key in which you will submit the form if Enter key was hit.
And now comes the problem with IE (in any case version 11)
Remark:
This issue does not exist with Chrome nor with FireFox !
When you click the submit button the form is submitted once; fine.
When you hit Enter the form is submitted twice ... and your servlet will be executed twice. If you don't have PRG (post redirect get) architecture serverside the result might be unexpected.
Even though the solution looks trivial, it tooks me many hours to solve this problem, so I hope it might be usefull for other folks.
This solution has been successfully tested, among others, on IE (v 11.0.9600.18426), FF (v 40.03) & Chrome (v 53.02785.143 m 64 bit)
The source code HTML & js are in the snippet. The principle is described there.
Warning:
You can't test it in the snippet because the post action is not
defined and hitting Enter key might interfer with stackoverflow.
If you faced this issue, then just copy/paste js code to your environment and adapt it to your context.
/*
* inForm points to the form
*/
var inForm = document.getElementById('idGetUserFrm');
/*
* IE submits the form twice
* To avoid this the boolean isSumbitted is:
* 1) initialized to false when the form is displayed 4 the first time
* Remark: it is not the same event as "body load"
*/
var isSumbitted = false;
function checkEnter(e) {
if (e && e.keyCode == 13) {
inForm.submit();
/*
* 2) set to true after the form submission was invoked
*/
isSumbitted = true;
}
}
function onSubmit () {
if (isSumbitted) {
/*
* 3) reset to false after the form submission executed
*/
isSumbitted = false;
return false;
}
}
<!DOCTYPE html>
<html>
<body>
<form id="idGetUserFrm" method="post" action="servletOrSomePhp" onsubmit="return onSubmit()">
First name:<br>
<input type="text" name="firstname" value="Mickey">
<input type="submit" value="Submit">
</form>
</body>
</html>

The best solution is onsubmit call any function whatever you want and return false after it.
onsubmit="xxx_xxx(); return false;"

Most people would prevent the form from submitting by calling the event.preventDefault() function.
Another means is to remove the onclick attribute of the button, and get the code in processForm() out into .submit(function() { as return false; causes the form to not submit. Also, make the formBlaSubmit() functions return Boolean based on validity, for use in processForm();
katsh's answer is the same, just easier to digest.
(By the way, I'm new to stackoverflow, give me guidance please. )

In pure Javascript, use: e.preventDefault()
e.preventDefault() is used in jquery but works in javascript.
document.querySelector(".buttonclick").addEventListener("click",
function(e){
//some code
e.preventDefault();
})

The best way to do so with JS is using preventDefault() function.
Consider the code below for reference:
function loadForm(){
var loginForm = document.querySelector('form'); //Selecting the form
loginForm.addEventListener('submit', login); //looking for submit
}
function login(e){
e.preventDefault(); //to stop form action i.e. submit
}

Personally I like to validate the form on submit and if there are errors, just return false.
$('form').submit(function() {
var error;
if ( !$('input').val() ) {
error = true
}
if (error) {
alert('there are errors')
return false
}
});
http://jsfiddle.net/dfyXY/

$("#buttonID").click(function (e) {
e.preventDefault();
//some logic here
}

If you want to use Pure Javascript then the following snippet will be better than anything else.
Suppose:
HTML:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Form Without Submiting With Pure JS</title>
<script type="text/javascript">
window.onload = function(){
/**
* Just Make sure to return false so that your request will not go the server script
*/
document.getElementById('simple_form').onsubmit = function(){
// After doing your logic that you want to do
return false
}
}
</script>
</head>
<body>
</body>
</html>
<form id="simple_form" method="post">
<!-- Your Inputs will go here -->
<input type="submit" value="Submit Me!!" />
</form>
Hope so it works for You!!

Just use "javascript:" in your action attribute of form if you are not using action.

In my opinion, most answers are trying to solve the problem asked on your question, but I don't think that's the best approach for your scenario.
How would I go about preventing the page from refreshing when pressing the send button without any data in the fields?
A .preventDefault() does indeed not refresh the page. But I think that a simple require on the fields you want populated with data, would solve your problem.
<form id="prospects_form" method="post">
<input id="form_name" tabindex="1" class="boxsize" type="text" name="name" placeholder="Full name*" maxlength="80" value="" required/>
<input id="form_email" tabindex="2" class="boxsize" type="text" name="email" placeholder="Email*" maxlength="100" value="" required/>
<input id="form_subject" class="boxsize" type="text" name="subject" placeholder="Subject*" maxlength="50" value="FORM: Row for OUBC" required/>
<textarea id="form_message" class="boxsize" name="message" placeholder="Message*" tabindex="3" rows="6" cols="5" maxlength="500"></textarea>
</form>
Notice the require tag added at the end of each input. The result will be the same: not refreshing the page without any data in the fields.

<form onsubmit="myFunction(event)">
Name : <input type="text"/>
<input class="submit" type="submit">
</form>
<script>
function myFunction(event){
event.preventDefault();
//code here
}
</script>

function ajax_form(selector, obj)
{
var form = document.querySelectorAll(selector);
if(obj)
{
var before = obj.before ? obj.before : function(){return true;};
var $success = obj.success ? obj.success: function(){return true;};
for (var i = 0; i < form.length; i++)
{
var url = form[i].hasAttribute('action') ? form[i].getAttribute('action') : window.location;
var $form = form[i];
form[i].submit = function()
{
var xhttp = new XMLHttpRequest();
xhttp.open("POST", url, true);
var FD = new FormData($form);
/** prevent submiting twice */
if($form.disable === true)
return this;
$form.disable = true;
if(before() === false)
return;
xhttp.addEventListener('load', function()
{
$form.disable = false;
return $success(JSON.parse(this.response));
});
xhttp.send(FD);
}
}
}
return form;
}
Didn't check how it works. You can also bind(this) so it will work like jquery ajaxForm
use it like:
ajax_form('form',
{
before: function()
{
alert('submiting form');
// if return false form shouldn't be submitted
},
success:function(data)
{
console.log(data)
}
}
)[0].submit();
it return nodes so you can do something like submit i above example
so far from perfection but it suppose to work, you should add error handling or remove disable condition

Sometimes e.preventDefault(); works then developers are happy but sometimes not work then developers are sad then I found solution why sometimes not works
first code sometimes works
$("#prospects_form").submit(function(e) {
e.preventDefault();
});
second option why not work?
This doesn't work because jquery or other javascript library not loading properly you can check it in console that all jquery and javascript files are loaded properly or not.
This solves my problem. I hope this will be helpful for you.

I hope this will be the last answer
$('#the_form').submit(function(e){
e.preventDefault()
alert($(this).serialize())
// var values = $(this).serialize()
// logic....
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form id="the_form">
Label-A <input type="text" name='a'required><br>
Label-B <input type="text" name="b" required><br>
Label-C <input type="password" name="c" required><br>
Label-D <input type="number" name="d" required><br>
<input type="submit" value="Save without refresh">
</form>

You can do this by clearing the state as below. add this to very beginning of the document.ready function.
if ( window.history.replaceState ) {
window.history.replaceState( null, null, window.location.href );
}

Javascript function gets called and then page resets back to initial state [duplicate]

How would I go about preventing the page from refreshing when pressing the send button without any data in the fields?
The validation is setup working fine, all fields go red but then the page is immediately refreshed. My knowledge of JS is relatively basic.
In particular I think the processForm() function at the bottom is 'bad'.
HTML
<form id="prospects_form" method="post">
<input id="form_name" tabindex="1" class="boxsize" type="text" name="name" placeholder="Full name*" maxlength="80" value="" />
<input id="form_email" tabindex="2" class="boxsize" type="text" name="email" placeholder="Email*" maxlength="100" value="" />
<input id="form_subject" class="boxsize" type="text" name="subject" placeholder="Subject*" maxlength="50" value="FORM: Row for OUBC" />
<textarea id="form_message" class="boxsize" name="message" placeholder="Message*" tabindex="3" rows="6" cols="5" maxlength="500"></textarea>
<button id="form_send" tabindex="5" class="btn" type="submit" onclick="return processForm()">Send</button>
<div id="form_validation">
<span class="form_captcha_code"></span>
<input id="form_captcha" class="boxsize" type="text" name="form_captcha" placeholder="Enter code" tabindex="4" value="" />
</div>
<div class="clearfix"></div>
</form>
JS
$(document).ready(function() {
// Add active class to inputs
$("#prospects_form .boxsize").focus(function() { $(this).addClass("hasText"); });
$("#form_validation .boxsize").focus(function() { $(this).parent().addClass("hasText"); });
// Remove active class from inputs (if empty)
$("#prospects_form .boxsize").blur(function() { if ( this.value === "") { $(this).removeClass("hasText"); } });
$("#form_validation .boxsize").blur(function() { if ( this.value === "") { $(this).parent().removeClass("hasText"); } });
///////////////////
// START VALIDATION
$("#prospects_form").ready(function() {
// DEFINE GLOBAL VARIABLES
var valName = $('#form_name'),
valEmail = $("#form_email"),
valEmailFormat = /^(([^<>()[\]\\.,;:\s#\"]+(\.[^<>()[\]\\.,;:\s#\"]+)*)|(\".+\"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/,
valMsg = $('#form_message'),
valCaptcha = $('#form_captcha'),
valCaptchaCode = $('.form_captcha_code');
// Generate captcha
function randomgen() {
var rannumber = "";
// Iterate through 1 to 9, 4 times
for(ranNum=1; ranNum<=4; ranNum++){ rannumber+=Math.floor(Math.random()*10).toString(); }
// Apply captcha to element
valCaptchaCode.html(rannumber);
}
randomgen();
// CAPTCHA VALIDATION
valCaptcha.blur(function() {
function formCaptcha() {
if ( valCaptcha.val() == valCaptchaCode.html() ) {
// Incorrect
valCaptcha.parent().addClass("invalid");
return false;
} else {
// Correct
valCaptcha.parent().removeClass("invalid");
return true;
}
}
formCaptcha();
});
// Remove invalid class from captcha if typing
valCaptcha.keypress(function() {
valCaptcha.parent().removeClass("invalid");
});
// EMAIL VALIDATION (BLUR)
valEmail.blur(function() {
function formEmail() {
if (!valEmailFormat.test(valEmail.val()) && valEmail.val() !== "" ) {
// Incorrect
valEmail.addClass("invalid");
} else {
// Correct
valEmail.removeClass("invalid");
}
}
formEmail();
});
// Remove invalid class from email if typing
valEmail.keypress(function() {
valEmail.removeClass("invalid");
});
// VALIDATION ON SUBMIT
$('#prospects_form').submit(function() {
console.log('user hit send button');
// EMAIL VALIDATION (SUBMIT)
function formEmailSubmit() {
if (!valEmailFormat.test(valEmail.val())) {
// Incorrect
valEmail.addClass("invalid");
} else {
// Correct
valEmail.removeClass("invalid");
}
}
formEmailSubmit();
// Validate captcha
function formCaptchaSubmit() {
if( valCaptcha.val() === valCaptchaCode.html() ) {
// Captcha is correct
} else {
// Captcha is incorrect
valCaptcha.parent().addClass("invalid");
randomgen();
}
}
formCaptchaSubmit();
// If NAME field is empty
function formNameSubmit() {
if ( valName.val() === "" ) {
// Name is empty
valName.addClass("invalid");
} else {
valName.removeClass("invalid");
}
}
formNameSubmit();
// If MESSAGE field is empty
function formMessageSubmit() {
if ( valMsg.val() === "" ) {
// Name is empty
valMsg.addClass("invalid");
} else {
valMsg.removeClass("invalid");
}
}
formMessageSubmit();
// Submit form (if all good)
function processForm() {
if ( formEmailSubmit() && formCaptchaSubmit() && formNameSubmit() && formMessageSubmit() ) {
$("#prospects_form").attr("action", "/clients/oubc/row-for-oubc-send.php");
$("#form_send").attr("type", "submit");
return true;
} else if( !formEmailSubmit() ) {
valEmail.addClass("invalid");
return false;
} else if ( !formCaptchaSubmit() ) {
valCaptcha.parent().addClass("invalid");
return false;
} else if ( !formNameSubmit() ) {
valName.addClass("invalid");
return false;
} else if ( !formMessageSubmit() ) {
valMsg.addClass("invalid");
return false;
} else {
return false;
}
}
});
});
// END VALIDATION
/////////////////
});

You can prevent the form from submitting with
$("#prospects_form").submit(function(e) {
e.preventDefault();
});
Of course, in the function, you can check for empty fields, and if anything doesn't look right, e.preventDefault() will stop the submit.
Without jQuery:
var form = document.getElementById("myForm");
function handleForm(event) { event.preventDefault(); }
form.addEventListener('submit', handleForm);

Add this onsubmit="return false" code:
<form onsubmit="return false">
That fixed it for me. It will still run the onClick function you specify.

Replace button type to button:
<button type="button">My Cool Button</button>

One great way to prevent reloading the page when submitting using a form is by adding return false with your onsubmit attribute.
<form onsubmit="yourJsFunction();return false">
<input type="text"/>
<input type="submit"/>
</form>

You can use this code for form submission without a page refresh. I have done this in my project.
$(function () {
$('#myFormName').on('submit',function (e) {
$.ajax({
type: 'post',
url: 'myPageName.php',
data: $('#myFormName').serialize(),
success: function () {
alert("Email has been sent!");
}
});
e.preventDefault();
});
});

This problem becomes more complex when you give the user 2 possibilities to submit the form:
by clicking on an ad hoc button
by hitting Enter key
In such a case you will need a function which detects the pressed key in which you will submit the form if Enter key was hit.
And now comes the problem with IE (in any case version 11)
Remark:
This issue does not exist with Chrome nor with FireFox !
When you click the submit button the form is submitted once; fine.
When you hit Enter the form is submitted twice ... and your servlet will be executed twice. If you don't have PRG (post redirect get) architecture serverside the result might be unexpected.
Even though the solution looks trivial, it tooks me many hours to solve this problem, so I hope it might be usefull for other folks.
This solution has been successfully tested, among others, on IE (v 11.0.9600.18426), FF (v 40.03) & Chrome (v 53.02785.143 m 64 bit)
The source code HTML & js are in the snippet. The principle is described there.
Warning:
You can't test it in the snippet because the post action is not
defined and hitting Enter key might interfer with stackoverflow.
If you faced this issue, then just copy/paste js code to your environment and adapt it to your context.
/*
* inForm points to the form
*/
var inForm = document.getElementById('idGetUserFrm');
/*
* IE submits the form twice
* To avoid this the boolean isSumbitted is:
* 1) initialized to false when the form is displayed 4 the first time
* Remark: it is not the same event as "body load"
*/
var isSumbitted = false;
function checkEnter(e) {
if (e && e.keyCode == 13) {
inForm.submit();
/*
* 2) set to true after the form submission was invoked
*/
isSumbitted = true;
}
}
function onSubmit () {
if (isSumbitted) {
/*
* 3) reset to false after the form submission executed
*/
isSumbitted = false;
return false;
}
}
<!DOCTYPE html>
<html>
<body>
<form id="idGetUserFrm" method="post" action="servletOrSomePhp" onsubmit="return onSubmit()">
First name:<br>
<input type="text" name="firstname" value="Mickey">
<input type="submit" value="Submit">
</form>
</body>
</html>

The best solution is onsubmit call any function whatever you want and return false after it.
onsubmit="xxx_xxx(); return false;"

Most people would prevent the form from submitting by calling the event.preventDefault() function.
Another means is to remove the onclick attribute of the button, and get the code in processForm() out into .submit(function() { as return false; causes the form to not submit. Also, make the formBlaSubmit() functions return Boolean based on validity, for use in processForm();
katsh's answer is the same, just easier to digest.
(By the way, I'm new to stackoverflow, give me guidance please. )

In pure Javascript, use: e.preventDefault()
e.preventDefault() is used in jquery but works in javascript.
document.querySelector(".buttonclick").addEventListener("click",
function(e){
//some code
e.preventDefault();
})

The best way to do so with JS is using preventDefault() function.
Consider the code below for reference:
function loadForm(){
var loginForm = document.querySelector('form'); //Selecting the form
loginForm.addEventListener('submit', login); //looking for submit
}
function login(e){
e.preventDefault(); //to stop form action i.e. submit
}

Personally I like to validate the form on submit and if there are errors, just return false.
$('form').submit(function() {
var error;
if ( !$('input').val() ) {
error = true
}
if (error) {
alert('there are errors')
return false
}
});
http://jsfiddle.net/dfyXY/

$("#buttonID").click(function (e) {
e.preventDefault();
//some logic here
}

If you want to use Pure Javascript then the following snippet will be better than anything else.
Suppose:
HTML:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Form Without Submiting With Pure JS</title>
<script type="text/javascript">
window.onload = function(){
/**
* Just Make sure to return false so that your request will not go the server script
*/
document.getElementById('simple_form').onsubmit = function(){
// After doing your logic that you want to do
return false
}
}
</script>
</head>
<body>
</body>
</html>
<form id="simple_form" method="post">
<!-- Your Inputs will go here -->
<input type="submit" value="Submit Me!!" />
</form>
Hope so it works for You!!

Just use "javascript:" in your action attribute of form if you are not using action.

In my opinion, most answers are trying to solve the problem asked on your question, but I don't think that's the best approach for your scenario.
How would I go about preventing the page from refreshing when pressing the send button without any data in the fields?
A .preventDefault() does indeed not refresh the page. But I think that a simple require on the fields you want populated with data, would solve your problem.
<form id="prospects_form" method="post">
<input id="form_name" tabindex="1" class="boxsize" type="text" name="name" placeholder="Full name*" maxlength="80" value="" required/>
<input id="form_email" tabindex="2" class="boxsize" type="text" name="email" placeholder="Email*" maxlength="100" value="" required/>
<input id="form_subject" class="boxsize" type="text" name="subject" placeholder="Subject*" maxlength="50" value="FORM: Row for OUBC" required/>
<textarea id="form_message" class="boxsize" name="message" placeholder="Message*" tabindex="3" rows="6" cols="5" maxlength="500"></textarea>
</form>
Notice the require tag added at the end of each input. The result will be the same: not refreshing the page without any data in the fields.

<form onsubmit="myFunction(event)">
Name : <input type="text"/>
<input class="submit" type="submit">
</form>
<script>
function myFunction(event){
event.preventDefault();
//code here
}
</script>

function ajax_form(selector, obj)
{
var form = document.querySelectorAll(selector);
if(obj)
{
var before = obj.before ? obj.before : function(){return true;};
var $success = obj.success ? obj.success: function(){return true;};
for (var i = 0; i < form.length; i++)
{
var url = form[i].hasAttribute('action') ? form[i].getAttribute('action') : window.location;
var $form = form[i];
form[i].submit = function()
{
var xhttp = new XMLHttpRequest();
xhttp.open("POST", url, true);
var FD = new FormData($form);
/** prevent submiting twice */
if($form.disable === true)
return this;
$form.disable = true;
if(before() === false)
return;
xhttp.addEventListener('load', function()
{
$form.disable = false;
return $success(JSON.parse(this.response));
});
xhttp.send(FD);
}
}
}
return form;
}
Didn't check how it works. You can also bind(this) so it will work like jquery ajaxForm
use it like:
ajax_form('form',
{
before: function()
{
alert('submiting form');
// if return false form shouldn't be submitted
},
success:function(data)
{
console.log(data)
}
}
)[0].submit();
it return nodes so you can do something like submit i above example
so far from perfection but it suppose to work, you should add error handling or remove disable condition

Sometimes e.preventDefault(); works then developers are happy but sometimes not work then developers are sad then I found solution why sometimes not works
first code sometimes works
$("#prospects_form").submit(function(e) {
e.preventDefault();
});
second option why not work?
This doesn't work because jquery or other javascript library not loading properly you can check it in console that all jquery and javascript files are loaded properly or not.
This solves my problem. I hope this will be helpful for you.

I hope this will be the last answer
$('#the_form').submit(function(e){
e.preventDefault()
alert($(this).serialize())
// var values = $(this).serialize()
// logic....
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form id="the_form">
Label-A <input type="text" name='a'required><br>
Label-B <input type="text" name="b" required><br>
Label-C <input type="password" name="c" required><br>
Label-D <input type="number" name="d" required><br>
<input type="submit" value="Save without refresh">
</form>

You can do this by clearing the state as below. add this to very beginning of the document.ready function.
if ( window.history.replaceState ) {
window.history.replaceState( null, null, window.location.href );
}

Prevent reload on form submit javascript [duplicate]

How would I go about preventing the page from refreshing when pressing the send button without any data in the fields?
The validation is setup working fine, all fields go red but then the page is immediately refreshed. My knowledge of JS is relatively basic.
In particular I think the processForm() function at the bottom is 'bad'.
HTML
<form id="prospects_form" method="post">
<input id="form_name" tabindex="1" class="boxsize" type="text" name="name" placeholder="Full name*" maxlength="80" value="" />
<input id="form_email" tabindex="2" class="boxsize" type="text" name="email" placeholder="Email*" maxlength="100" value="" />
<input id="form_subject" class="boxsize" type="text" name="subject" placeholder="Subject*" maxlength="50" value="FORM: Row for OUBC" />
<textarea id="form_message" class="boxsize" name="message" placeholder="Message*" tabindex="3" rows="6" cols="5" maxlength="500"></textarea>
<button id="form_send" tabindex="5" class="btn" type="submit" onclick="return processForm()">Send</button>
<div id="form_validation">
<span class="form_captcha_code"></span>
<input id="form_captcha" class="boxsize" type="text" name="form_captcha" placeholder="Enter code" tabindex="4" value="" />
</div>
<div class="clearfix"></div>
</form>
JS
$(document).ready(function() {
// Add active class to inputs
$("#prospects_form .boxsize").focus(function() { $(this).addClass("hasText"); });
$("#form_validation .boxsize").focus(function() { $(this).parent().addClass("hasText"); });
// Remove active class from inputs (if empty)
$("#prospects_form .boxsize").blur(function() { if ( this.value === "") { $(this).removeClass("hasText"); } });
$("#form_validation .boxsize").blur(function() { if ( this.value === "") { $(this).parent().removeClass("hasText"); } });
///////////////////
// START VALIDATION
$("#prospects_form").ready(function() {
// DEFINE GLOBAL VARIABLES
var valName = $('#form_name'),
valEmail = $("#form_email"),
valEmailFormat = /^(([^<>()[\]\\.,;:\s#\"]+(\.[^<>()[\]\\.,;:\s#\"]+)*)|(\".+\"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/,
valMsg = $('#form_message'),
valCaptcha = $('#form_captcha'),
valCaptchaCode = $('.form_captcha_code');
// Generate captcha
function randomgen() {
var rannumber = "";
// Iterate through 1 to 9, 4 times
for(ranNum=1; ranNum<=4; ranNum++){ rannumber+=Math.floor(Math.random()*10).toString(); }
// Apply captcha to element
valCaptchaCode.html(rannumber);
}
randomgen();
// CAPTCHA VALIDATION
valCaptcha.blur(function() {
function formCaptcha() {
if ( valCaptcha.val() == valCaptchaCode.html() ) {
// Incorrect
valCaptcha.parent().addClass("invalid");
return false;
} else {
// Correct
valCaptcha.parent().removeClass("invalid");
return true;
}
}
formCaptcha();
});
// Remove invalid class from captcha if typing
valCaptcha.keypress(function() {
valCaptcha.parent().removeClass("invalid");
});
// EMAIL VALIDATION (BLUR)
valEmail.blur(function() {
function formEmail() {
if (!valEmailFormat.test(valEmail.val()) && valEmail.val() !== "" ) {
// Incorrect
valEmail.addClass("invalid");
} else {
// Correct
valEmail.removeClass("invalid");
}
}
formEmail();
});
// Remove invalid class from email if typing
valEmail.keypress(function() {
valEmail.removeClass("invalid");
});
// VALIDATION ON SUBMIT
$('#prospects_form').submit(function() {
console.log('user hit send button');
// EMAIL VALIDATION (SUBMIT)
function formEmailSubmit() {
if (!valEmailFormat.test(valEmail.val())) {
// Incorrect
valEmail.addClass("invalid");
} else {
// Correct
valEmail.removeClass("invalid");
}
}
formEmailSubmit();
// Validate captcha
function formCaptchaSubmit() {
if( valCaptcha.val() === valCaptchaCode.html() ) {
// Captcha is correct
} else {
// Captcha is incorrect
valCaptcha.parent().addClass("invalid");
randomgen();
}
}
formCaptchaSubmit();
// If NAME field is empty
function formNameSubmit() {
if ( valName.val() === "" ) {
// Name is empty
valName.addClass("invalid");
} else {
valName.removeClass("invalid");
}
}
formNameSubmit();
// If MESSAGE field is empty
function formMessageSubmit() {
if ( valMsg.val() === "" ) {
// Name is empty
valMsg.addClass("invalid");
} else {
valMsg.removeClass("invalid");
}
}
formMessageSubmit();
// Submit form (if all good)
function processForm() {
if ( formEmailSubmit() && formCaptchaSubmit() && formNameSubmit() && formMessageSubmit() ) {
$("#prospects_form").attr("action", "/clients/oubc/row-for-oubc-send.php");
$("#form_send").attr("type", "submit");
return true;
} else if( !formEmailSubmit() ) {
valEmail.addClass("invalid");
return false;
} else if ( !formCaptchaSubmit() ) {
valCaptcha.parent().addClass("invalid");
return false;
} else if ( !formNameSubmit() ) {
valName.addClass("invalid");
return false;
} else if ( !formMessageSubmit() ) {
valMsg.addClass("invalid");
return false;
} else {
return false;
}
}
});
});
// END VALIDATION
/////////////////
});

You can prevent the form from submitting with
$("#prospects_form").submit(function(e) {
e.preventDefault();
});
Of course, in the function, you can check for empty fields, and if anything doesn't look right, e.preventDefault() will stop the submit.
Without jQuery:
var form = document.getElementById("myForm");
function handleForm(event) { event.preventDefault(); }
form.addEventListener('submit', handleForm);

Add this onsubmit="return false" code:
<form onsubmit="return false">
That fixed it for me. It will still run the onClick function you specify.

Replace button type to button:
<button type="button">My Cool Button</button>

One great way to prevent reloading the page when submitting using a form is by adding return false with your onsubmit attribute.
<form onsubmit="yourJsFunction();return false">
<input type="text"/>
<input type="submit"/>
</form>

You can use this code for form submission without a page refresh. I have done this in my project.
$(function () {
$('#myFormName').on('submit',function (e) {
$.ajax({
type: 'post',
url: 'myPageName.php',
data: $('#myFormName').serialize(),
success: function () {
alert("Email has been sent!");
}
});
e.preventDefault();
});
});

This problem becomes more complex when you give the user 2 possibilities to submit the form:
by clicking on an ad hoc button
by hitting Enter key
In such a case you will need a function which detects the pressed key in which you will submit the form if Enter key was hit.
And now comes the problem with IE (in any case version 11)
Remark:
This issue does not exist with Chrome nor with FireFox !
When you click the submit button the form is submitted once; fine.
When you hit Enter the form is submitted twice ... and your servlet will be executed twice. If you don't have PRG (post redirect get) architecture serverside the result might be unexpected.
Even though the solution looks trivial, it tooks me many hours to solve this problem, so I hope it might be usefull for other folks.
This solution has been successfully tested, among others, on IE (v 11.0.9600.18426), FF (v 40.03) & Chrome (v 53.02785.143 m 64 bit)
The source code HTML & js are in the snippet. The principle is described there.
Warning:
You can't test it in the snippet because the post action is not
defined and hitting Enter key might interfer with stackoverflow.
If you faced this issue, then just copy/paste js code to your environment and adapt it to your context.
/*
* inForm points to the form
*/
var inForm = document.getElementById('idGetUserFrm');
/*
* IE submits the form twice
* To avoid this the boolean isSumbitted is:
* 1) initialized to false when the form is displayed 4 the first time
* Remark: it is not the same event as "body load"
*/
var isSumbitted = false;
function checkEnter(e) {
if (e && e.keyCode == 13) {
inForm.submit();
/*
* 2) set to true after the form submission was invoked
*/
isSumbitted = true;
}
}
function onSubmit () {
if (isSumbitted) {
/*
* 3) reset to false after the form submission executed
*/
isSumbitted = false;
return false;
}
}
<!DOCTYPE html>
<html>
<body>
<form id="idGetUserFrm" method="post" action="servletOrSomePhp" onsubmit="return onSubmit()">
First name:<br>
<input type="text" name="firstname" value="Mickey">
<input type="submit" value="Submit">
</form>
</body>
</html>

The best solution is onsubmit call any function whatever you want and return false after it.
onsubmit="xxx_xxx(); return false;"

Most people would prevent the form from submitting by calling the event.preventDefault() function.
Another means is to remove the onclick attribute of the button, and get the code in processForm() out into .submit(function() { as return false; causes the form to not submit. Also, make the formBlaSubmit() functions return Boolean based on validity, for use in processForm();
katsh's answer is the same, just easier to digest.
(By the way, I'm new to stackoverflow, give me guidance please. )

In pure Javascript, use: e.preventDefault()
e.preventDefault() is used in jquery but works in javascript.
document.querySelector(".buttonclick").addEventListener("click",
function(e){
//some code
e.preventDefault();
})

The best way to do so with JS is using preventDefault() function.
Consider the code below for reference:
function loadForm(){
var loginForm = document.querySelector('form'); //Selecting the form
loginForm.addEventListener('submit', login); //looking for submit
}
function login(e){
e.preventDefault(); //to stop form action i.e. submit
}

Personally I like to validate the form on submit and if there are errors, just return false.
$('form').submit(function() {
var error;
if ( !$('input').val() ) {
error = true
}
if (error) {
alert('there are errors')
return false
}
});
http://jsfiddle.net/dfyXY/

$("#buttonID").click(function (e) {
e.preventDefault();
//some logic here
}

If you want to use Pure Javascript then the following snippet will be better than anything else.
Suppose:
HTML:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Form Without Submiting With Pure JS</title>
<script type="text/javascript">
window.onload = function(){
/**
* Just Make sure to return false so that your request will not go the server script
*/
document.getElementById('simple_form').onsubmit = function(){
// After doing your logic that you want to do
return false
}
}
</script>
</head>
<body>
</body>
</html>
<form id="simple_form" method="post">
<!-- Your Inputs will go here -->
<input type="submit" value="Submit Me!!" />
</form>
Hope so it works for You!!

Just use "javascript:" in your action attribute of form if you are not using action.

In my opinion, most answers are trying to solve the problem asked on your question, but I don't think that's the best approach for your scenario.
How would I go about preventing the page from refreshing when pressing the send button without any data in the fields?
A .preventDefault() does indeed not refresh the page. But I think that a simple require on the fields you want populated with data, would solve your problem.
<form id="prospects_form" method="post">
<input id="form_name" tabindex="1" class="boxsize" type="text" name="name" placeholder="Full name*" maxlength="80" value="" required/>
<input id="form_email" tabindex="2" class="boxsize" type="text" name="email" placeholder="Email*" maxlength="100" value="" required/>
<input id="form_subject" class="boxsize" type="text" name="subject" placeholder="Subject*" maxlength="50" value="FORM: Row for OUBC" required/>
<textarea id="form_message" class="boxsize" name="message" placeholder="Message*" tabindex="3" rows="6" cols="5" maxlength="500"></textarea>
</form>
Notice the require tag added at the end of each input. The result will be the same: not refreshing the page without any data in the fields.

<form onsubmit="myFunction(event)">
Name : <input type="text"/>
<input class="submit" type="submit">
</form>
<script>
function myFunction(event){
event.preventDefault();
//code here
}
</script>

function ajax_form(selector, obj)
{
var form = document.querySelectorAll(selector);
if(obj)
{
var before = obj.before ? obj.before : function(){return true;};
var $success = obj.success ? obj.success: function(){return true;};
for (var i = 0; i < form.length; i++)
{
var url = form[i].hasAttribute('action') ? form[i].getAttribute('action') : window.location;
var $form = form[i];
form[i].submit = function()
{
var xhttp = new XMLHttpRequest();
xhttp.open("POST", url, true);
var FD = new FormData($form);
/** prevent submiting twice */
if($form.disable === true)
return this;
$form.disable = true;
if(before() === false)
return;
xhttp.addEventListener('load', function()
{
$form.disable = false;
return $success(JSON.parse(this.response));
});
xhttp.send(FD);
}
}
}
return form;
}
Didn't check how it works. You can also bind(this) so it will work like jquery ajaxForm
use it like:
ajax_form('form',
{
before: function()
{
alert('submiting form');
// if return false form shouldn't be submitted
},
success:function(data)
{
console.log(data)
}
}
)[0].submit();
it return nodes so you can do something like submit i above example
so far from perfection but it suppose to work, you should add error handling or remove disable condition

Sometimes e.preventDefault(); works then developers are happy but sometimes not work then developers are sad then I found solution why sometimes not works
first code sometimes works
$("#prospects_form").submit(function(e) {
e.preventDefault();
});
second option why not work?
This doesn't work because jquery or other javascript library not loading properly you can check it in console that all jquery and javascript files are loaded properly or not.
This solves my problem. I hope this will be helpful for you.

I hope this will be the last answer
$('#the_form').submit(function(e){
e.preventDefault()
alert($(this).serialize())
// var values = $(this).serialize()
// logic....
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form id="the_form">
Label-A <input type="text" name='a'required><br>
Label-B <input type="text" name="b" required><br>
Label-C <input type="password" name="c" required><br>
Label-D <input type="number" name="d" required><br>
<input type="submit" value="Save without refresh">
</form>

You can do this by clearing the state as below. add this to very beginning of the document.ready function.
if ( window.history.replaceState ) {
window.history.replaceState( null, null, window.location.href );
}

I want the user to not be able to advance to the next screen if he/she doesn't enter the required information

The function receives the username and password of the user. If either are left empty, nothing happens and they won't be linked to google.ca if they click the "Go" button. If they filed in the required sections then they will be directed to google.ca. For some reason, if any of the text boxes are left unfilled and the Go button is pressed, it brings me to a 404 error page when I want it to just stay on that page until the user fills the textbox. What is causing this problem? This is the HTML file.
<form action="index.php" method="get" id="form" onsubmit="return go(document.getElementById('username'), document.getElementById('password'))">
<table>
<tr><td>Username: <input type="text" name="username" maxlength="16" id="username" onKeyUp="updateLength('username', 'usernameLength')" onblur="checkTextField(this);"/> <span id="usernameLength"></span></td></tr>
<tr><td>Password: <input type="password" name="password" maxlength="50" id="password" onKeyUp="updateLength('password', 'passwordLength')"> <span id="passwordLength" onblur="checkTextField(this);"></span></td></tr>
<tr><td><input type="submit" value="Go" id="goButton" onclick="go(username, password)"/></td></tr>
</table>
</form>
And here is the js file
function loginFunction() {
var url = "login.html";
window.open(url);
}
function createAccountFunction() {
var url2 = "createAccount.html";
window.open(url2);
}
function go(username, password) {
if (username != null && password != null) {
var url = "https://www.google.ca/";
window.open(url);
}
}
function updateLength(field, output) {
var curr_length = document.getElementById(field).value.length;
var field_mLen = document.getElementById(field).maxLength;
document.getElementById(output).innerHTML = curr_length + '/' + field_mLen;
}
function checkTextField(field) {
if (field.value == '')
alert("Field is empty");
}

You aren't stopping the default event of the onsubmit. You can do that by changing your go function to:
function go(username, password) {
return function(event) {
event.preventDefault();
if (username != null && password != null) {
var url = "https://www.google.ca/";
window.open(url);
}
}
}
You also don't need the return in the HTML. Just call the function.

I didn't understand your code logic, but maybe I can offer you a way to fix your code by yourself.
You have a form and a button. If you click on the button you execute the go() function. Because the button is a submit button, on the same click you execute one more time the go() function.
My advice is to create a new function, you may name it validate():
function validate() {
var username = document.get........
var password = document.get........
// more logic here, if need
if(!username || !password) {
return false;
}
return true
}
and now, your submit button looks like:
<input type="submit" value="Go" id="goButton" onclick="return validate()"/>
The form won't submit if the validate() function returns false.
Hope this helps.

Stop form refreshing page on submit

How would I go about preventing the page from refreshing when pressing the send button without any data in the fields?
The validation is setup working fine, all fields go red but then the page is immediately refreshed. My knowledge of JS is relatively basic.
In particular I think the processForm() function at the bottom is 'bad'.
HTML
<form id="prospects_form" method="post">
<input id="form_name" tabindex="1" class="boxsize" type="text" name="name" placeholder="Full name*" maxlength="80" value="" />
<input id="form_email" tabindex="2" class="boxsize" type="text" name="email" placeholder="Email*" maxlength="100" value="" />
<input id="form_subject" class="boxsize" type="text" name="subject" placeholder="Subject*" maxlength="50" value="FORM: Row for OUBC" />
<textarea id="form_message" class="boxsize" name="message" placeholder="Message*" tabindex="3" rows="6" cols="5" maxlength="500"></textarea>
<button id="form_send" tabindex="5" class="btn" type="submit" onclick="return processForm()">Send</button>
<div id="form_validation">
<span class="form_captcha_code"></span>
<input id="form_captcha" class="boxsize" type="text" name="form_captcha" placeholder="Enter code" tabindex="4" value="" />
</div>
<div class="clearfix"></div>
</form>
JS
$(document).ready(function() {
// Add active class to inputs
$("#prospects_form .boxsize").focus(function() { $(this).addClass("hasText"); });
$("#form_validation .boxsize").focus(function() { $(this).parent().addClass("hasText"); });
// Remove active class from inputs (if empty)
$("#prospects_form .boxsize").blur(function() { if ( this.value === "") { $(this).removeClass("hasText"); } });
$("#form_validation .boxsize").blur(function() { if ( this.value === "") { $(this).parent().removeClass("hasText"); } });
///////////////////
// START VALIDATION
$("#prospects_form").ready(function() {
// DEFINE GLOBAL VARIABLES
var valName = $('#form_name'),
valEmail = $("#form_email"),
valEmailFormat = /^(([^<>()[\]\\.,;:\s#\"]+(\.[^<>()[\]\\.,;:\s#\"]+)*)|(\".+\"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/,
valMsg = $('#form_message'),
valCaptcha = $('#form_captcha'),
valCaptchaCode = $('.form_captcha_code');
// Generate captcha
function randomgen() {
var rannumber = "";
// Iterate through 1 to 9, 4 times
for(ranNum=1; ranNum<=4; ranNum++){ rannumber+=Math.floor(Math.random()*10).toString(); }
// Apply captcha to element
valCaptchaCode.html(rannumber);
}
randomgen();
// CAPTCHA VALIDATION
valCaptcha.blur(function() {
function formCaptcha() {
if ( valCaptcha.val() == valCaptchaCode.html() ) {
// Incorrect
valCaptcha.parent().addClass("invalid");
return false;
} else {
// Correct
valCaptcha.parent().removeClass("invalid");
return true;
}
}
formCaptcha();
});
// Remove invalid class from captcha if typing
valCaptcha.keypress(function() {
valCaptcha.parent().removeClass("invalid");
});
// EMAIL VALIDATION (BLUR)
valEmail.blur(function() {
function formEmail() {
if (!valEmailFormat.test(valEmail.val()) && valEmail.val() !== "" ) {
// Incorrect
valEmail.addClass("invalid");
} else {
// Correct
valEmail.removeClass("invalid");
}
}
formEmail();
});
// Remove invalid class from email if typing
valEmail.keypress(function() {
valEmail.removeClass("invalid");
});
// VALIDATION ON SUBMIT
$('#prospects_form').submit(function() {
console.log('user hit send button');
// EMAIL VALIDATION (SUBMIT)
function formEmailSubmit() {
if (!valEmailFormat.test(valEmail.val())) {
// Incorrect
valEmail.addClass("invalid");
} else {
// Correct
valEmail.removeClass("invalid");
}
}
formEmailSubmit();
// Validate captcha
function formCaptchaSubmit() {
if( valCaptcha.val() === valCaptchaCode.html() ) {
// Captcha is correct
} else {
// Captcha is incorrect
valCaptcha.parent().addClass("invalid");
randomgen();
}
}
formCaptchaSubmit();
// If NAME field is empty
function formNameSubmit() {
if ( valName.val() === "" ) {
// Name is empty
valName.addClass("invalid");
} else {
valName.removeClass("invalid");
}
}
formNameSubmit();
// If MESSAGE field is empty
function formMessageSubmit() {
if ( valMsg.val() === "" ) {
// Name is empty
valMsg.addClass("invalid");
} else {
valMsg.removeClass("invalid");
}
}
formMessageSubmit();
// Submit form (if all good)
function processForm() {
if ( formEmailSubmit() && formCaptchaSubmit() && formNameSubmit() && formMessageSubmit() ) {
$("#prospects_form").attr("action", "/clients/oubc/row-for-oubc-send.php");
$("#form_send").attr("type", "submit");
return true;
} else if( !formEmailSubmit() ) {
valEmail.addClass("invalid");
return false;
} else if ( !formCaptchaSubmit() ) {
valCaptcha.parent().addClass("invalid");
return false;
} else if ( !formNameSubmit() ) {
valName.addClass("invalid");
return false;
} else if ( !formMessageSubmit() ) {
valMsg.addClass("invalid");
return false;
} else {
return false;
}
}
});
});
// END VALIDATION
/////////////////
});

You can prevent the form from submitting with
$("#prospects_form").submit(function(e) {
e.preventDefault();
});
Of course, in the function, you can check for empty fields, and if anything doesn't look right, e.preventDefault() will stop the submit.
Without jQuery:
var form = document.getElementById("myForm");
function handleForm(event) { event.preventDefault(); }
form.addEventListener('submit', handleForm);

Add this onsubmit="return false" code:
<form onsubmit="return false">
That fixed it for me. It will still run the onClick function you specify.

Replace button type to button:
<button type="button">My Cool Button</button>

One great way to prevent reloading the page when submitting using a form is by adding return false with your onsubmit attribute.
<form onsubmit="yourJsFunction();return false">
<input type="text"/>
<input type="submit"/>
</form>

You can use this code for form submission without a page refresh. I have done this in my project.
$(function () {
$('#myFormName').on('submit',function (e) {
$.ajax({
type: 'post',
url: 'myPageName.php',
data: $('#myFormName').serialize(),
success: function () {
alert("Email has been sent!");
}
});
e.preventDefault();
});
});

This problem becomes more complex when you give the user 2 possibilities to submit the form:
by clicking on an ad hoc button
by hitting Enter key
In such a case you will need a function which detects the pressed key in which you will submit the form if Enter key was hit.
And now comes the problem with IE (in any case version 11)
Remark:
This issue does not exist with Chrome nor with FireFox !
When you click the submit button the form is submitted once; fine.
When you hit Enter the form is submitted twice ... and your servlet will be executed twice. If you don't have PRG (post redirect get) architecture serverside the result might be unexpected.
Even though the solution looks trivial, it tooks me many hours to solve this problem, so I hope it might be usefull for other folks.
This solution has been successfully tested, among others, on IE (v 11.0.9600.18426), FF (v 40.03) & Chrome (v 53.02785.143 m 64 bit)
The source code HTML & js are in the snippet. The principle is described there.
Warning:
You can't test it in the snippet because the post action is not
defined and hitting Enter key might interfer with stackoverflow.
If you faced this issue, then just copy/paste js code to your environment and adapt it to your context.
/*
* inForm points to the form
*/
var inForm = document.getElementById('idGetUserFrm');
/*
* IE submits the form twice
* To avoid this the boolean isSumbitted is:
* 1) initialized to false when the form is displayed 4 the first time
* Remark: it is not the same event as "body load"
*/
var isSumbitted = false;
function checkEnter(e) {
if (e && e.keyCode == 13) {
inForm.submit();
/*
* 2) set to true after the form submission was invoked
*/
isSumbitted = true;
}
}
function onSubmit () {
if (isSumbitted) {
/*
* 3) reset to false after the form submission executed
*/
isSumbitted = false;
return false;
}
}
<!DOCTYPE html>
<html>
<body>
<form id="idGetUserFrm" method="post" action="servletOrSomePhp" onsubmit="return onSubmit()">
First name:<br>
<input type="text" name="firstname" value="Mickey">
<input type="submit" value="Submit">
</form>
</body>
</html>

The best solution is onsubmit call any function whatever you want and return false after it.
onsubmit="xxx_xxx(); return false;"

Most people would prevent the form from submitting by calling the event.preventDefault() function.
Another means is to remove the onclick attribute of the button, and get the code in processForm() out into .submit(function() { as return false; causes the form to not submit. Also, make the formBlaSubmit() functions return Boolean based on validity, for use in processForm();
katsh's answer is the same, just easier to digest.
(By the way, I'm new to stackoverflow, give me guidance please. )

In pure Javascript, use: e.preventDefault()
e.preventDefault() is used in jquery but works in javascript.
document.querySelector(".buttonclick").addEventListener("click",
function(e){
//some code
e.preventDefault();
})

The best way to do so with JS is using preventDefault() function.
Consider the code below for reference:
function loadForm(){
var loginForm = document.querySelector('form'); //Selecting the form
loginForm.addEventListener('submit', login); //looking for submit
}
function login(e){
e.preventDefault(); //to stop form action i.e. submit
}

Personally I like to validate the form on submit and if there are errors, just return false.
$('form').submit(function() {
var error;
if ( !$('input').val() ) {
error = true
}
if (error) {
alert('there are errors')
return false
}
});
http://jsfiddle.net/dfyXY/

$("#buttonID").click(function (e) {
e.preventDefault();
//some logic here
}

If you want to use Pure Javascript then the following snippet will be better than anything else.
Suppose:
HTML:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Form Without Submiting With Pure JS</title>
<script type="text/javascript">
window.onload = function(){
/**
* Just Make sure to return false so that your request will not go the server script
*/
document.getElementById('simple_form').onsubmit = function(){
// After doing your logic that you want to do
return false
}
}
</script>
</head>
<body>
</body>
</html>
<form id="simple_form" method="post">
<!-- Your Inputs will go here -->
<input type="submit" value="Submit Me!!" />
</form>
Hope so it works for You!!

Just use "javascript:" in your action attribute of form if you are not using action.

In my opinion, most answers are trying to solve the problem asked on your question, but I don't think that's the best approach for your scenario.
How would I go about preventing the page from refreshing when pressing the send button without any data in the fields?
A .preventDefault() does indeed not refresh the page. But I think that a simple require on the fields you want populated with data, would solve your problem.
<form id="prospects_form" method="post">
<input id="form_name" tabindex="1" class="boxsize" type="text" name="name" placeholder="Full name*" maxlength="80" value="" required/>
<input id="form_email" tabindex="2" class="boxsize" type="text" name="email" placeholder="Email*" maxlength="100" value="" required/>
<input id="form_subject" class="boxsize" type="text" name="subject" placeholder="Subject*" maxlength="50" value="FORM: Row for OUBC" required/>
<textarea id="form_message" class="boxsize" name="message" placeholder="Message*" tabindex="3" rows="6" cols="5" maxlength="500"></textarea>
</form>
Notice the require tag added at the end of each input. The result will be the same: not refreshing the page without any data in the fields.

<form onsubmit="myFunction(event)">
Name : <input type="text"/>
<input class="submit" type="submit">
</form>
<script>
function myFunction(event){
event.preventDefault();
//code here
}
</script>

function ajax_form(selector, obj)
{
var form = document.querySelectorAll(selector);
if(obj)
{
var before = obj.before ? obj.before : function(){return true;};
var $success = obj.success ? obj.success: function(){return true;};
for (var i = 0; i < form.length; i++)
{
var url = form[i].hasAttribute('action') ? form[i].getAttribute('action') : window.location;
var $form = form[i];
form[i].submit = function()
{
var xhttp = new XMLHttpRequest();
xhttp.open("POST", url, true);
var FD = new FormData($form);
/** prevent submiting twice */
if($form.disable === true)
return this;
$form.disable = true;
if(before() === false)
return;
xhttp.addEventListener('load', function()
{
$form.disable = false;
return $success(JSON.parse(this.response));
});
xhttp.send(FD);
}
}
}
return form;
}
Didn't check how it works. You can also bind(this) so it will work like jquery ajaxForm
use it like:
ajax_form('form',
{
before: function()
{
alert('submiting form');
// if return false form shouldn't be submitted
},
success:function(data)
{
console.log(data)
}
}
)[0].submit();
it return nodes so you can do something like submit i above example
so far from perfection but it suppose to work, you should add error handling or remove disable condition

Sometimes e.preventDefault(); works then developers are happy but sometimes not work then developers are sad then I found solution why sometimes not works
first code sometimes works
$("#prospects_form").submit(function(e) {
e.preventDefault();
});
second option why not work?
This doesn't work because jquery or other javascript library not loading properly you can check it in console that all jquery and javascript files are loaded properly or not.
This solves my problem. I hope this will be helpful for you.

I hope this will be the last answer
$('#the_form').submit(function(e){
e.preventDefault()
alert($(this).serialize())
// var values = $(this).serialize()
// logic....
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form id="the_form">
Label-A <input type="text" name='a'required><br>
Label-B <input type="text" name="b" required><br>
Label-C <input type="password" name="c" required><br>
Label-D <input type="number" name="d" required><br>
<input type="submit" value="Save without refresh">
</form>

You can do this by clearing the state as below. add this to very beginning of the document.ready function.
if ( window.history.replaceState ) {
window.history.replaceState( null, null, window.location.href );
}

Develop Reference

JavaScript is the programming language of the Web.

Onclick event; If and Else - javascript

The event needs to cancel the default event and return false. This will prevent the form from submitting. HOWEVER, it should be a non-issue if the form submits anyway, because JavaScript CANNOT be trusted and therefore you MUST validate all input server-side.

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