Develop Reference

Attempting to prevent submitting empty form

I have a form in my HTML document, and it only has a "text" input, and a submit button.
I also have JavaScript that checks if the field is empty and returns true or false.
JSFiddle: http://jsfiddle.net/HBZ7t/
HTML:
<form onsubmit="checkNull();" method="post">
<input type="text" id="field">
<input type="submit">
</form>
JavaScript
function checkNull() {
var field = document.getElementById("field");
if(field.value !== "") {
return true;
}
return false;
}
However, the form can be submitted even if the text field is empty... Any suggestions?

You are doing nearly everything right, you just need to return the value from the function to the handler:
<form onsubmit="return checkNull();" method="post">
// -------------^^^^^^

In JavaScript you can use double exclamation points to check for lots of non-valid settings:
function checkNull() {
var field = document.getElementById("field");
if(!!field.value) {
return true;
} else {
return false;
};

FIDDLE
JS
var form=document.getElementById("form");
form.onsubmit=function(){
var field = document.getElementById("field");
if (field.value !== "") {
return true;
}
return false;
};
HTML
<form id="form" method="post">
<input type="text" id="field">
<input type="submit">
</form>

you can use event.preventDefault() to cancel a event, see mozila doc here
Also, check the very nice jQuery submit function and samples here
Check this sample: http://jsfiddle.net/HBZ7t/5/
$( "#target" ).submit(function( event ) {
if($('#field').val()=='')
{
alert('cancel event');
event.preventDefault();
}
});

Textbox value compare before submitting

I want to let my two textboxes be checked before those get submitted.
like
if textbox1 >= textbox2 submit
else show errorlabel and dont submit.
How can i do this?

Provide your onclick handler's implementation to extract the value of the two text boxes, then parse them as an int.
function submitForm() {
var first = parseInt(document.getElementById("first"), 0);
var second = parseInt(document.getElementById("second"), 0);
if(first >= second) {
// ...
return true;
} else {
var hiddenTextBox = document.getElementById("error");
hiddenTextBox.style.visibility = "visible";
return false;
}
}
This assumes you have two elements with id="first" and id="second" respectively, and a hidden element with id="error"

Try it like,
$('#submitId').on('click',function(){
if $('#textbox1').val() < $('#textbox2').val()){
$('#erroLabel').show(); // showing error label
return false; // to prevent submitting form
}
});

You can make function in javascript,
<script type="text/javascript">
function checkValues()
{
var searchtext1 = document.getElementById("textbox1").value;
if(searchtext1=='')
{
alert('Enter any character');
return false;
}
var searchtext2 = document.getElementById("textbox2").value;
if(searchtext2=='')
{
alert('Enter any character');
return false;
}
}
</script>
and then in html form
<form method='GET' onSubmit="return checkValues();">
<input type="text" id= "textbox1" name="textbox1" class='textbox' >
<input type="text" id= "textbox2" name="textbox2" class='textbox' >
<input type="submit" id='submit' value="Search" class ='button' >
</form>

Form validation problems

I have a very strange problem. Inside form I have hidden input with value -1 and input field for username.
<form action="" method="POST" name="login" onSubmit="return Validate()">
<input type="text" id="username"/>
<input type="hidden" id="available" value="-1"/>
< input type="submit" value="Send"/>
</form>
On submit function Validate() checks value of username input which mustn't be empty, and Validate() also checks value of available input which mustn't be valued -1.
function Validate(){
var a=document.getElementById("username").value;
var b=document.getElementById("available").value;
if(a=="" || a==null)
{
alert("Username cannot be empty");
return false;
}
else if(b<0)
{
alert("Form isn't finished");
return false;
}
else
{
return true;
}
}
Problem is that Validate() works only if one condition is evalueted. If function Validate() contains only 1 var(a or b) and 1 if order(without else if) it works correctly. But when I put it like this, when Validate uses a and b variables and if, else if conditional order it won't work. Really od.. Thanks in advance...
In this case it works:
function Validate(){
var a=document.getElementById("username").value;
if(a=="" || a==null)
{
alert("Username cannot be empty");
return false;
}
else
{
return true;
}
}

<input type="hidden" id="available" value="-1"/>
Here the value is of string dataType. Whereas
else if(b<0) //b is string dataType
Hence it failed. so change it as
var b= Number(document.getElementById("available").value);
Try like this
HTML:
<form action="" method="POST" name="login">
<input type="text" id="username" />
<input type="hidden" id="available" value="1" />
<input type="button" value="Send" onClick="return Validate()" />
</form>
JS:
function Validate() {
var a = document.getElementById("username").value;
var b = Number(document.getElementById("available").value);
if (a == "" || a == null) {
alert("Username cannot be empty");
return false;
} else if (b < 0) {
alert("Form isn't finished");
return false;
} else {
document.login.submit(); //dynamically submit the form
}
}

If you are wanting to get error notifications for each input don't use if/else here, use multiple if's and set your errors
function validate(){
var a=document.getElementById("username").value;
var b=document.getElementById("available").value;
var errors = [];
if(a=="" || a==null){
errors.push("Invalid username");
}
if(b<0 || isNaN(b)){
errors.push("Invalid available value");
}
if(errors.length>0) {
//do something with errors (like display them
return false;
}
}
Using the else if one of them evaluates to true it will skip the others. For instance if the first one is empty or null then it will do that block and skip the others.

I was testing your code for IE and Firefox and it work. Just add parseInt when you get the value of var b.
var b= parseInt(document.getElementById("available").value);

Javascript alert on submit if text field is empty

So i want to alert the user if they submit the form with an empty text field
HTML:
<form id="orderform">
<input type="text" name="initials" id="initials" maxlength="3">
<p class="center">
<input type="image" src="#" id="submitbutton" name="submit" value="Place Order">
</p>
</form>
Javascript:
$('#orderform').submit(function() {
if($('#initials').length == 0){
alert('Please fill out your initials.');
}
});

Just make sure you return false in there somewhere-
$('#orderform').submit(function() {
if($('#initials').val() == ''){
alert('Please fill out your initials.');
return false;
}
});

$('#initials').length will check if the element exists. Try this:
$('#orderform').submit(function() {
if($('#initials').val().length == 0){
alert('Please fill out your initials.');
}
});
as lewsid pointed out, you should also return false if you want to cancel the submit

$('#orderform').submit(function(e) {
e.preventDefault();
if(!$.trim((this + ' input').val()).length){
alert('Please fill all the fields');
return false;
}
return true;
});
but is better if you do this with pure JS not jQuery
function funnjsTrim(input) {
return input
.replace(/^\s\s*/, '')
.replace(/\s\s*$/, '')
.replace(/([\s]+)/g, '-');
}
validate_form = function(form, mssg){
mssg = form_errors[mssg] || 'Error: empty field';
var form_to = form.name,
elems = document.forms[form_to].getElementsByTagName("input");
for(var i = 0; i < elems.length + 1; i++) {
if(elems[i].type != 'submit') {
var string = funnjsTrim(elems[i].value);
if(!string.length) {
alert(mssg);
error = 'error';
return false
}
}
}
if(typeof error == "undefined"){
alert('Valid');
return true;
}
}
so in your html
<form onsubmit="return validate_form(this)">
in this line: if(elems[i].type != 'submit') add || elems[i].class != 'your input class' to add exceptions

I'd use e.preventDefault() instead of return false. Return false also prevents events from bubbling and can have unintended consequences if you don't understand this. Also nest that preventDefault within your if, no reason to stop submission if things are good.
$('#orderform').submit(function(e) {
if(!$.trim($(this).find('input[type="text"]').val()).length){
e.preventDefault();
alert('Please fill all the fields');
}
});

validation of input text field in html using javascript

<script type='text/javascript'>
function required()
{
var empt = document.forms["form1"]["Name"].value;
if (empt == "")
{
alert("Please input a Value");
return false;
}
}
</script>
<form name="form1" method="" action="">
<input type="text" name="name" value="Name"/><br />
<input type="text" name="address line1" value="Address Line 1"/><br />
I have more than one input text field, each having their default value. Before I submit the form I have to verify whether all fields are filled. So far i got the javascript to check for null since different text boxes have different default value. How can I write a javascript to verify that user has entered data? I mean, the script must identify that input data is other than default and null.

If you are not using jQuery then I would simply write a validation method that you can be fired when the form is submitted. The method can validate the text fields to make sure that they are not empty or the default value. The method will return a bool value and if it is false you can fire off your alert and assign classes to highlight the fields that did not pass validation.
HTML:
<form name="form1" method="" action="" onsubmit="return validateForm(this)">
<input type="text" name="name" value="Name"/><br />
<input type="text" name="addressLine01" value="Address Line 1"/><br />
<input type="submit"/>
</form>
JavaScript:
function validateForm(form) {
var nameField = form.name;
var addressLine01 = form.addressLine01;
if (isNotEmpty(nameField)) {
if(isNotEmpty(addressLine01)) {
return true;
{
{
return false;
}
function isNotEmpty(field) {
var fieldData = field.value;
if (fieldData.length == 0 || fieldData == "" || fieldData == fieldData) {
field.className = "FieldError"; //Classs to highlight error
alert("Please correct the errors in order to continue.");
return false;
} else {
field.className = "FieldOk"; //Resets field back to default
return true; //Submits form
}
}
The validateForm method assigns the elements you want to validate and then in this case calls the isNotEmpty method to validate if the field is empty or has not been changed from the default value. it continuously calls the inNotEmpty method until it returns a value of true or if the conditional fails for that field it will return false.
Give this a shot and let me know if it helps or if you have any questions. of course you can write additional custom methods to validate numbers only, email address, valid URL, etc.
If you use jQuery at all I would look into trying out the jQuery Validation plug-in. I have been using it for my last few projects and it is pretty nice. Check it out if you get a chance. http://docs.jquery.com/Plugins/Validation

<form name="myForm" id="myForm" method="post" onsubmit="return validateForm();">
First Name: <input type="text" id="name" /> <br />
<span id="nameErrMsg" class="error"></span> <br />
<!-- ... all your other stuff ... -->
</form>
<p>
1.word should be atleast 5 letter<br>
2.No space should be encountered<br>
3.No numbers and special characters allowed<br>
4.letters can be repeated upto 3(eg: aa is allowed aaa is not allowed)
</p>
<button id="validateTestButton" value="Validate now" onclick="validateForm();">Validate now</button>
validateForm = function () {
return checkName();
}
function checkName() {
var x = document.myForm;
var input = x.name.value;
var errMsgHolder = document.getElementById('nameErrMsg');
if (input.length < 5) {
errMsgHolder.innerHTML =
'Please enter a name with at least 5 letters';
return false;
} else if (!(/^\S{3,}$/.test(input))) {
errMsgHolder.innerHTML =
'Name cannot contain whitespace';
return false;
}else if(!(/^[a-zA-Z]+$/.test(input)))
{
errMsgHolder.innerHTML=
'Only alphabets allowed'
}
else if(!(/^(?:(\w)(?!\1\1))+$/.test(input)))
{
errMsgHolder.innerHTML=
'per 3 alphabets allowed'
}
else {
errMsgHolder.innerHTML = '';
return undefined;
}
}
.error {
color: #E00000;
}

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Validation</title>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script type="text/javascript">
var tags = document.getElementsByTagName("input");
var radiotags = document.getElementsByName("gender");
var compareValidator = ['compare'];
var formtag = document.getElementsByTagName("form");
function validation(){
for(var i=0;i<tags.length;i++){
var tagid = tags[i].id;
var tagval = tags[i].value;
var tagtit = tags[i].title;
var tagclass = tags[i].className;
//Validation for Textbox Start
if(tags[i].type == "text"){
if(tagval == "" || tagval == null){
var lbl = $(tags[i]).prev().text();
lbl = lbl.replace(/ : /g,'')
//alert("Please Enter "+lbl);
$(".span"+tagid).remove();
$("#"+tagid).after("<span style='color:red;' class='span"+tagid+"'>Please Enter "+lbl+"</span>");
$("#"+tagid).focus();
//return false;
}
else if(tagval != "" || tagval != null){
$(".span"+tagid).remove();
}
//Validation for compare text in two text boxes Start
//put two tags with same class name and put class name in compareValidator.
for(var j=0;j<compareValidator.length;j++){
if((tagval != "") && (tagclass.indexOf(compareValidator[j]) != -1)){
if(($('.'+compareValidator[j]).first().val()) != ($('.'+compareValidator[j]).last().val())){
$("."+compareValidator[j]+":last").after("<span style='color:red;' class='span"+tagid+"'>Invalid Text</span>");
$("span").prev("span").remove();
$("."+compareValidator[j]+":last").focus();
//return false;
}
}
}
//Validation for compare text in two text boxes End
//Validation for Email Start
if((tagval != "") && (tagclass.indexOf('email') != -1)){
//enter class = email where you want to use email validator
var reg = /^\w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*$/
if (reg.test(tagval)){
$(".span"+tagid).remove();
return true;
}
else{
$(".span"+tagid).remove();
$("#"+tagid).after("<span style='color:red;' class='span"+tagid+"'>Email is Invalid</span>");
$("#"+tagid).focus();
return false;
}
}
//Validation for Email End
}
//Validation for Textbox End
//Validation for Radio Start
else if(tags[i].type == "radio"){
//enter class = gender where you want to use gender validator
if((radiotags[0].checked == false) && (radiotags[1].checked == false)){
$(".span"+tagid).remove();
//$("#"+tagid").after("<span style='color:red;' class='span"+tagid+"'>Please Select Your Gender </span>");
$(".gender:last").next().after("<span style='color:red;' class='span"+tagid+"'> Please Select Your Gender</span>");
$("#"+tagid).focus();
i += 1;
}
else{
$(".span"+tagid).remove();
}
}
//Validation for Radio End
else{
}
}
//return false;
}
function Validate(){
if(!validation()){
return false;
}
return true;
}
function onloadevents(){
tags[tags.length -1].onclick = function(){
//return Validate();
}
for(var j=0;j<formtag.length;j++){
formtag[j].onsubmit = function(){
return Validate();
}
}
for(var i=0;i<tags.length;i++){
var tagid = tags[i].id;
var tagval = tags[i].value;
var tagtit = tags[i].title;
var tagclass = tags[i].className;
if((tags[i].type == "text") && (tagclass.indexOf('numeric') != -1)){
//enter class = numeric where you want to use numeric validator
document.getElementById(tagid).onkeypress = function(){
numeric(event);
}
}
}
}
function numeric(event){
var KeyBoardCode = (event.which) ? event.which : event.keyCode;
if (KeyBoardCode > 31 && (KeyBoardCode < 48 || KeyBoardCode > 57)){
event.preventDefault();
$(".spannum").remove();
//$(".numeric").after("<span class='spannum'>Numeric Keys Please</span>");
//$(".numeric").focus();
return false;
}
$(".spannum").remove();
return true;
}
if (document.addEventListener) {
document.addEventListener("DOMContentLoaded", onloadevents, false);
}
//window.onload = onloadevents;
</script>
</head>
<body>
<form method="post">
<label for="fname">Test 1 : </label><input type="text" title="Test 1" id="fname" class="form1"><br>
<label for="fname1">Test 2 : </label><input type="text" title="Test 2" id="fname1" class="form1 compare"><br>
<label for="fname2">Test 3 : </label><input type="text" title="Test 3" id="fname2" class="form1 compare"><br>
<label for="gender">Gender : </label>
<input type="radio" title="Male" id="fname3" class="gender" name="gender" value="Male"><label for="gender">Male</label>
<input type="radio" title="Female" id="fname4" class="gender" name="gender" value="Female"><label for="gender">Female</label><br>
<label for="fname5">Mobile : </label><input type="text" title="Mobile" id="fname5" class="numeric"><br>
<label for="fname6">Email : </label><input type="text" title="Email" id="fname6" class="email"><br>
<input type="submit" id="sub" value="Submit">
</form>
</body>
</html>

function hasValue( val ) { // Return true if text input is valid/ not-empty
return val.replace(/\s+/, '').length; // boolean
}
For multiple elements you can pass inside your input elements loop their value into that function argument.
If a user inserted one or more spaces, thanks to the regex s+ the function will return false.

<pre><form name="myform" action="saveNew" method="post" enctype="multipart/form-data">
<input type="text" id="name" name="name" />
<input type="submit"/>
</form></pre>
<script language="JavaScript" type="text/javascript">
var frmvalidator = new Validator("myform");
frmvalidator.EnableFocusOnError(false);
frmvalidator.EnableMsgsTogether();
frmvalidator.addValidation("name","req","Plese Enter Name");
</script>
before using above code you have to add the gen_validatorv31.js js file

For flexibility and other places you might want to validated. You can use the following function.
`function validateOnlyTextField(element) {
var str = element.value;
if(!(/^[a-zA-Z, ]+$/.test(str))){
// console.log('String contain number characters');
str = str.substr(0, str.length -1);
element.value = str;
}
}`
Then on your html section use the following event.
<input type="text" id="names" onkeyup="validateOnlyTextField(this)" />
You can always reuse the function.