Develop Reference

Check input field is empty or not

I am going to create simple validation form using Vanilla JavaScript, but I have problem, I want to check first ('entername') field, if user will not enter any letters in it, i want to console log message ('enter name'), it's works fine, but after that user reenter his name if field it returns in console ('enter name'), i want to return ('not enter') message.
var userBtn = document.getElementById('checkuserinputs');
var checkUserName = document.getElementById('user-name').value;
var checkUserSurname = document.getElementById('user-surname').value;
var checkUserPhone = document.getElementById('user-mobile').value;
userBtn.addEventListener('click', function(){
if(checkUserName.length == 0){
console.log('enter name')
}else{
console.log('not enter')
}
})
<div class="container-fluid">
<div class="modal-costum-row">
<div class="enter-name-side">
<div class="input-row">
<input class="costum--input" type="text" id="user-name" name="user-nm" placeholder="entername">
</div>
</div>
<div class="enter-surname-side">
<div class="input-row">
<input class="costum--input" type="text" id="user-surname" name="surname" placeholder="entersurname">
</div>
</div>
</div>
<div class="enter-tel-numb-side">
<div class="input-row input--wide">
<input class="costum--input" type="tel" id="user-mobile" name="user-mobile" placeholder="enterphonenumber">
</div>
</div>
</div>
<button id="checkuserinputs">check input</button>

You need to get the value after clicking the button. If you put it outside of the click event, the value will never be updated.
var userBtn = document.getElementById('checkuserinputs');
userBtn.addEventListener('click', function () {
var checkUserName = document.getElementById('user-name').value;
var checkUserSurname = document.getElementById('user-surname').value;
var checkUserPhone = document.getElementById('user-mobile').value;
if (checkUserName.length == 0) {
console.log('enter name')
} else {
console.log('not enter')
}
})
<div class="container-fluid">
<div class="modal-costum-row">
<div class="enter-name-side">
<div class="input-row">
<input class="costum--input" type="text" id="user-name" name="user-nm" placeholder="entername" />
</div>
</div>
<div class="enter-surname-side">
<div class="input-row">
<input class="costum--input" type="text" id="user-surname" name="surname" placeholder="entersurname" />
</div>
</div>
</div>
<div class="enter-tel-numb-side">
<div class="input-row input--wide">
<input class="costum--input" type="tel" id="user-mobile" name="user-mobile" placeholder="enterphonenumber" />
</div>
</div>
</div>
<button id="checkuserinputs">check input</button>

You need to retrieve the value of the input field in the click function callback:
userBtn.addEventListener('click', () => {
const checkUserName = document.getElementById('user-name').value;
if(checkUserName.length === 0){
console.log('enter name')
} else {
console.log('not enter')
}
})

change the variable geting value to button click function that is,
var userBtn = document.getElementById('checkuserinputs');
userBtn.addEventListener('click', function(){
var checkUserName = document.getElementById('user-name').value;
var checkUserSurname = document.getElementById('user-surname').value;
var checkUserPhone = document.getElementById('user-mobile').value;
if(!checkUserName){
console.log('enter name')
}else{
console.log('not enter')
}
})
var userBtn = document.getElementById('checkuserinputs');
userBtn.addEventListener('click', function(){
var checkUserName = document.getElementById('user-name').value;
var checkUserSurname = document.getElementById('user-surname').value;
var checkUserPhone = document.getElementById('user-mobile').value;
if(!checkUserName){
console.log('enter name')
}else{
console.log('not enter')
}
})
<div class="container-fluid">
<div class="modal-costum-row">
<div class="enter-name-side">
<div class="input-row">
<input class="costum--input" type="text" id="user-name" name="user-nm" placeholder="entername">
</div>
</div>
<div class="enter-surname-side">
<div class="input-row">
<input class="costum--input" type="text" id="user-surname" name="surname" placeholder="entersurname">
</div>
</div>
</div>
<div class="enter-tel-numb-side">
<div class="input-row input--wide">
<input class="costum--input" type="tel" id="user-mobile" name="user-mobile" placeholder="enterphonenumber">
</div>
</div>
</div>
<button id="checkuserinputs">check input</button>

How to display form validation error messages accurately for more than two input fields using only JavaScript?

I have created a JavaScript function that checks a form during submitting the input and displays an error message if there's no input.
It works perfectly when none input is given. It displays all the error messages correctly.
The Problem: But if I leave just the first field blank i.e, the fullname; the if loop stops there and doesn't display the second or third error messages i.e, the streetaddr & quantity.
NOTE: This error happens only when one of streetaddr or quantity is not given with addition to the first field i.e, fullname.
What should I do to display the error messages correctly. According to the blank input regardless the input field comes first or second or third.
Also, I prefer to do this with just Vanilla JavaScript, no frameworks/libraries. I'm trying to learn!
Link(s): This is a challenge from Wikiversity
/* Checking form function */
function checkForm(){
window.alert("You clicked Submit!");
var fullNameCheck = document.getElementById("fullname");
var addressCheck = document.getElementById("streetaddr");
var quantityCheck = document.getElementById("quantity");
var is_valid = false;
/* If statements to check if text box is empty */
if (fullNameCheck.value=="" && addressCheck.value=="" && quantityCheck.value=="") {
document.getElementById("nameerrormsg").style.display="inline";
document.getElementById("addrerrormsg").style.display="inline";
document.getElementById("qtyerrormsg").style.display="inline";
is_valid = false;
} else if(fullNameCheck.value==""){
document.getElementById("nameerrormsg").style.display="inline";
document.getElementById("addrerrormsg").style.display="none";
document.getElementById("qtyerrormsg").style.display="none";
is_valid = false;
} else if (addressCheck.value==""){
document.getElementById("addrerrormsg").style.display="inline";
document.getElementById("nameerrormsg").style.display="none";
document.getElementById("qtyerrormsg").style.display="none";
is_valid = false;
} else if (quantityCheck.value==""){
document.getElementById("qtyerrormsg").style.display="inline";
document.getElementById("nameerrormsg").style.display="none";
document.getElementById("addrerrormsg").style.display="none";
is_valid = false;
} else {
document.getElementById("nameerrormsg").style.display="none";
document.getElementById("addrerrormsg").style.display="none";
document.getElementById("qtyerrormsg").style.display="none";
is_valid = true;
} return is_valid;
}
.errormsg{
color: red;
background-color: yellow;
display: none;
}
<form action="mailto:me#fakeemail.com" onsubmit="return checkForm();">
<fieldset>
<legend>Personal details</legend>
<p>
<label>
Full name:
<input type="text" name="fullname" id="fullname">
</label>
</p>
<p class="errormsg" id="nameerrormsg">Please enter your name above</p>
<p>
<label>
Street Address:
<input type="text" name="streetaddr" id="streetaddr">
</label>
</p>
<p class="errormsg" id="addrerrormsg">Please enter your street address</p>
<!-- Quantity input -->
<p>
<label>
Quantity:
<input type="text" name="quantity" id="quantity">
</label>
</p>
<p class="errormsg" id="qtyerrormsg">Please enter your quantity</p>
</fieldset>
<input type="submit" value="Submit it!">
</form>

I'd prefer to just make the fields required, no Javascript needed:
<form action="mailto:me#fakeemail.com" onsubmit="return checkForm();">
<fieldset>
<legend>Personal details</legend>
<p>
<label>
Full name:
<input type="text" name="fullname" id="fullname" required>
</label>
</p>
<p>
<label>
Street Address:
<input type="text" name="streetaddr" id="streetaddr" required>
</label>
</p>
<!-- Quantity input -->
<p>
<label>
Quantity:
<input type="text" name="quantity" id="quantity" required>
</label>
</p>
</fieldset>
<input type="submit" value="Submit it!">
</form>
Otherwise, you can first hide all the error messages. Iterate over all inputs in the form, and if invalid (missing), navigate to its ancestor p and then to the adjacent .errormsg and set its display.
It would also be a good idea to avoid inline handlers entirely, they have too many problems to be worth using. Attach listeners properly using addEventListener in Javascript instead.
document.querySelector('form').addEventListener('submit', () => {
for (const errormsg of document.querySelectorAll('.errormsg')) {
errormsg.style.display = 'none';
}
let valid = true;
for (const input of document.querySelectorAll('form input')) {
if (input.value) {
// valid
continue;
}
valid = false;
input.closest('p').nextElementSibling.style.display = 'inline';
}
return valid;
});
.errormsg{
color: red;
background-color: yellow;
display: none;
}
<form action="mailto:me#fakeemail.com">
<fieldset>
<legend>Personal details</legend>
<p>
<label>
Full name:
<input type="text" name="fullname" id="fullname">
</label>
</p>
<p class="errormsg" id="nameerrormsg">Please enter your name above</p>
<p>
<label>
Street Address:
<input type="text" name="streetaddr" id="streetaddr">
</label>
</p>
<p class="errormsg" id="addrerrormsg">Please enter your street address</p>
<!-- Quantity input -->
<p>
<label>
Quantity:
<input type="text" name="quantity" id="quantity">
</label>
</p>
<p class="errormsg" id="qtyerrormsg">Please enter your quantity</p>
</fieldset>
<input type="submit" value="Submit it!">
</form>

You could hide all the error text as initially. Then show the error text based on respected input failure
/* Checking form function */
function checkForm() {
window.alert("You clicked Submit!");
var fullNameCheck = document.getElementById("fullname");
var addressCheck = document.getElementById("streetaddr");
var quantityCheck = document.getElementById("quantity");
var is_valid = false;
/* If statements to check if text box is empty */
document.getElementById("nameerrormsg").style.display = "none";
document.getElementById("addrerrormsg").style.display = "none";
document.getElementById("qtyerrormsg").style.display = "none";
is_valid = true;
if (fullNameCheck.value == "") {
document.getElementById("nameerrormsg").style.display = "inline";
is_valid = false;
}
if (addressCheck.value == "") {
document.getElementById("addrerrormsg").style.display = "inline";
is_valid = false;
}
if (quantityCheck.value == "") {
document.getElementById("qtyerrormsg").style.display = "inline";
is_valid = false;
}
return is_valid;
}
.errormsg {
color: red;
background-color: yellow;
display: none;
}
<form action="mailto:me#fakeemail.com" onsubmit="return checkForm();">
<fieldset>
<legend>Personal details</legend>
<p>
<label>
Full name:
<input type="text" name="fullname" id="fullname">
</label>
</p>
<p class="errormsg" id="nameerrormsg">Please enter your name above</p>
<p>
<label>
Street Address:
<input type="text" name="streetaddr" id="streetaddr">
</label>
</p>
<p class="errormsg" id="addrerrormsg">Please enter your street address</p>
<!-- Quantity input -->
<p>
<label>
Quantity:
<input type="text" name="quantity" id="quantity">
</label>
</p>
<p class="errormsg" id="qtyerrormsg">Please enter your quantity</p>
</fieldset>
<input type="submit" value="Submit it!">
</form>

Several input checkbox using one JS with different var

I have 3 input checkboxes. Each of them displays a div if checked. Because the three has the same JS I have decided to have just one JS including 3 variables (one per input) but it is not working. Before I had three independent JS and it worked fine.
CODE
document.getElementById()
var cb1 = document.getElementById('checkbox1'); checkbox1.onchange = {
if (checkbox1.checked) {
course1.style.display = 'block';
} else {
course1.style.display = 'none';
};
var cb2 = document.getElementById('checkbox2'); checkbox2.onchange = {
if (checkbox2.checked) {
course2.style.display = 'block';
} else {
course2.style.display = 'none';
};
var cb3 = document.getElementById('checkbox3'); checkbox3.onchange = {
if (checkbox3.checked) {
course3.style.display = 'block';
} else {
course3.style.display = 'none';
};
<form>
<label class="switch">
<input type="checkbox" id="checkbox1"> Course 1
</label>
</form>
<form>
<label class="switch">
<input type="checkbox" id="checkbox2"> Course 2
</label>
</form>
<form>
<label class="switch">
<input type="checkbox" id="checkbox3"> Course 3
</label>
</form>
<br>
<div id ="course1">
Text course 1
</div>
<br>
<div id ="course2">
Text course 2
</div>
<br>
<div id ="course3">
Text course 3
</div>
Fiddle: https://codepen.io/antonioagar1/pen/YOwBeE?editors=1010

After fixing your syntax errors (identation is very imporant, if it was correct in your code you would had see that you have many if statements not closing correclty)
Well, besides those errors, I managed a way to you that you only need a single function to achieve your desired result.
If you see in the HTML part, you'll note that I added some new attributes to checkboxes and divs, called data-idCheck, where the checkbox with data-idCheck will display the div whose have that same attribute.
Check below to see if my code helps you.
var cb1 = document.getElementById('checkbox1');
cb1.onchange = checkChecked;
var cb2 = document.getElementById('checkbox2');
cb2.onchange = checkChecked;
var cb3 = document.getElementById('checkbox3');
cb3.onchange = checkChecked;
function checkChecked(){
let idCheck = this.getAttribute("data-idCheck");
let relatedDiv = document.querySelector("div[data-idCheck='" + idCheck + "']");
if (this.checked) {
relatedDiv.style.display = 'block';
} else {
relatedDiv.style.display = 'none';
}
}
.hiddenDiv{
display: none;
}
<form>
<label class="switch">
<input type="checkbox" id="checkbox1" data-idCheck="1"> Course 1
</label>
</form>
<form>
<label class="switch">
<input type="checkbox" id="checkbox2" data-idCheck="2"> Course 2
</label>
</form>
<form>
<label class="switch">
<input type="checkbox" id="checkbox3" data-idCheck="3"> Course 3
</label>
</form>
<br>
<div id ="course1" class="hiddenDiv" data-idCheck="1">
Text course 1
</div>
<br>
<div id ="course2" class="hiddenDiv" data-idCheck="2">
Text course 2
</div>
<br>
<div id ="course3" class="hiddenDiv" data-idCheck="3">
Text course 3
</div>

how dynamically add new button by javascript

I have two textboxes and one button,
I want to add one new textfield, that should show card name from textbox1 and Link URL append from textbox2 when I click on button
//AddnNewCardNavigator
var counter=2;
var nmecardtxt= document.getElementById("textbox1").value;
var linkurltxt= document.getElementById("textbox2").value;
$("#addbutton").click(function(){
if(nmecardtxt ==""||nmecardtxt ==0||nmecardtxt ==null
&& linkurltxt ==""||linkurltxt ==""|| linkurltxt ==0||linkurltxt ==null){
alert("Please insert value in Card name and Link Url textboxes and must be correct");
return false;
}
var NewCarddiv = $(document.createElement('div')).attr("id",'cardlink'+counter);
NewCarddiv.after().html()
})
</script>
<!-- text boxes-->
<div class="row">
<div class="col-md-12">
<div id="textboxesgroup">
<div id="textboxdiv1">
<label style="color:blanchedalmond">Card Name: </label><input type="textbox" id="textbox1">
</div>
<div id="textboxdiv2">
<label style="color:blanchedalmond">Link Url:    </label><input type="textbox" id="textbox2">
</div>
</div>
</div>
</div>

Your variables nmecardtxt and linkurltxt must be created inside the click function,
because it's empty at the loading of the page.
I also took the liberty to use jQuery for that variables, as you're already using it, and tried to enhance some other things:
(See comments in my code for details)
//AddnNewCardNavigator
var counter = 2;
// On click function
$("#addbutton").click(function() {
// Here it's better
var nmecardtxt = $("#textbox1").val();
var linkurltxt = $("#textbox2").val();
// Modified you test here
if (!nmecardtxt || !linkurltxt) {
alert("Please insert value in Card name and Link Url textboxes and must be correct");
return false;
}
// Modified creation of the card
var link = $(document.createElement('a')).attr("href", linkurltxt).html(linkurltxt);
var NewCarddiv = $(document.createElement('div')).attr("id", 'cardlink' + counter).html(nmecardtxt + ": ").append(link);
$('#cards').append(NewCarddiv);
//NewCarddiv.after().html(); // Was that line an attempt of the above ?
});
body {
background: #888;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<!-- text boxes-->
<div class="row">
<div class="col-md-12">
<div id="textboxesgroup">
<div id="textboxdiv1">
<label style="color:blanchedalmond">Card Name: </label><input type="textbox" id="textbox1">
</div>
<div id="textboxdiv2">
<label style="color:blanchedalmond">Link Url:   </label><input type="textbox" id="textbox2">
</div>
</div>
</div>
</div>
<!-- Added the below -->
<div id="cards">
</div>
<button id="addbutton">Add…</button>
Hope it helps.

Here's a simplified version of what you're trying to accomplish:
function addNewCard() {
var name = $('#name').val();
var url = $('#url').val();
var count = $('#cards > .card').length;
if (!name || !url) {
alert('Missing name and/or URL.');
}
var card = $('<div class="card"></div>').html("Name: " + name + "<br>URL: " + url);
$("#cards").append(card);
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<label for="name">Name:</label>
<input type="text" id="name" name="name">
<label for="url">URL:</label>
<input type="text" id="url" name="url">
<input type="submit" value="Add Card" onclick="addNewCard();">
<div id="cards">
</div>

Javascript Error message flashes for only a second [duplicate]

This question already has answers here:
What is the meaning of onsubmit="return false"? (JavaScript, jQuery)
(4 answers)
Closed 5 years ago.
I have this HTML project that validates an empty form. The error is being displayed on the side of the inputs but only flashes for a second. I just want the error of the messages to be displayed once
This is my HTML code with the necessary links:
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>JavaScript - JQuery </title>
<link rel="stylesheet" type="text/css" href="contactform.css">
</head>
<body>
<h1 id="pageheading">Zedland Health Authority</h1>
<h2 class="sectionheading">Contact Form</h2>
<form id="register">
<fieldset id="controls">
<div>
<label class="formlabel" for="fname">First Name: </label>
<input id="fname" type="text" size="30" placeholder="First name"
autofocus>
<p id="fname-error" class="error" style="display:none; color:red;">*
You must enter a first name.</p>
</div>
<div>
<label class="formlabel"for="lname">Last Name: </label>
<input id="lname" type="text" size="30">
<p id="lname-error" class="error" style="display:none; color:red;">*
You must enter a Last name.</p>
</div>
<div>
<label class="formlabel" for="title">Title: </label>
<select id="title">
<option value="Mr">Mr.</option>
<option value="Ms">Ms.</option>
<option value="Mrs">Mrs.</option>
<option value="Miss">Miss.</option>
<option value="Master">Master.</option>
</select>
</div>
<div>
<label class="formlabel" for="heathauthoritynumber"><span>
<img src="tooltip.png" id="qmark" alt="Hint"></span>
Health Authority Number:
</label>
<input id="healthauthoritynumber" type="text" size="10">
<p id="hn-error" class="error" style="display:none; color:red;">*You
must enter a Health Authority Number eg('ZHA345742)</p>
<div class="tooltip" id="ttip">If you do not know your ZHA number
,please contact your GP</div>
</div>
<div>
<label class="formlabel" for="email">Email: </label>
<input id="email" type="text" size="40">
<p id="email-error" class="error" style="display:none; color:red;">You
must enter email</p>
</div>
<div>
<label class="formlabel" for="telephone">Telephone Number: </label>
<input id="telephone" type="text" size="40">
<p id="tele-error" class="error" style="display:none; color:red;">You
must enter a telephone</p>
</div>
<div class="formlabel">
<input id="submit-button" type="submit" value="Submit" >
</div>
</fieldset>
</form>
<script src="contactform.js"></script>
</body>
</html>
This is my Javascript
function onSubmit(){
console.log("ive been submitted");
checkEmpty(document.getElementById('fname'),document.getElementById("fname-error"));
checkEmpty(document.getElementById('lname'),document.getElementById("lname-error"));
checkEmpty(document.getElementById('healthauthoritynumber'),document.getElementById("hn-error"));
checkEmpty(document.getElementById('email'),document.getElementById("email-error"));
checkEmpty(document.getElementById('telephone'),document.getElementById("tele-error"));
//checkValidHealthID(document.getElementById('healthauthoritynumber'),document.getElementById("hn-error"));
}
// Read about regular expressions using: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions
// and http://stackoverflow.com/questions/25155970/validating-uk-phone-number-regex-c
function checkValidHealthID(inputID, errorID){
var re = new RegExp('/ZHA\d{6}$/');
if((inputID.value)!== re){
errorID.style.display = "inline";
}else
{
errorID.style.display = "none";
}
}
function checkEmpty(inputID, errorID){
//Default behaviour at for FORM is to reload the HTML page
//e.preventDefault();
console.log("checking empty");
if((inputID.value === "") || (inputID.value.length === 0)){
console.log("empty!!");
errorID.style.display = "inline";
}
else
{
errorID.style.display = "none";
}
}
function textHint(txtElem, defaultText) {
txtElem.value = defaultText;
txtElem.style.color = "#A8A8A8";
txtElem.style.fontStyle = "italic";
txtElem.onfocus = function() {
if (this.value === defaultText) {
this.value = "";
this.style.color = "#000";
this.style.fontStyle = "normal";
}
}
txtElem.onblur = function() {
if (this.value === "") {
this.value = defaultText;
this.style.color = "#A8A8A8";
this.style.fontStyle = "italic";
}
}
}
function textHints() {
//textHint(document.getElementById("firstName"), "Enter your first name");
textHint(document.getElementById('lname'), "Enter your last name");
textHint(document.getElementById('healthauthoritynumber'), "for eg
,ZHA346783");
textHint(document.getElementById('email'), "Enter your email");
textHint(document.getElementById('telephone'), "Enter your telephone
number");
}
function switchToolTip() {
document.getElementById('qmark').onmouseover = function() {
var toolTip = document.getElementById('ttip');
toolTip.style.display='block';
}
document.getElementById('qmark').onmouseout = function() {
var toolTip = document.getElementById('ttip');
toolTip.style.display='none';
}
}
//windows.onload=textHints();
//windows.onload=switchToolTip();
//window.onload=init;
document.getElementById("submit-button").onclick = onSubmit;

Your form is getting submitted which results in page reload. That's why you see the message flashing for a while. I saw the commented line in your JavaScript
//Default behaviour at for FORM is to reload the HTML page
//e.preventDefault();
You should get uncomment e.preventDefault().
Grab the click event as function onSubmit(event) and pass the event to checkEmpty.