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Firebase not creating users [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 );
}

Enable Disabled Button if Input is not empty

I have one simple form which have two fields called first name with id fname and email field with email. I have submit button with id called submit-btn.
I have disabled submit button using javascript like this
document.getElementById("submit-btn").disabled = true;
Now I am looking for allow submit if both of my fields are filled.
My full javascript is like this
<script type="text/javascript">
document.getElementById("submit-btn").disabled = true;
document.getElementById("submit-btn").onclick = function(){
window.open("https://google.com",'_blank');
}
</script>
I am learning javascript and does not know how I can do it. Let me know if someone here can help me for same.
Thanks!

Id propose something like this
Use a block, which encapsulates the names of variables and functions inside the block scope
Make small functions, which do just one thing
Prefer addEventListener over onclick or onanything
There are two types of events you could use on the inputs: input and change. input will react on every keystroke, check will only react, if you blur the input element
I added a check for validity to the email field with checkValidity method
{
const btn = document.getElementById("submit-btn");
const fname = document.getElementById("fname");
const email = document.getElementById("email");
deactivate()
function activate() {
btn.disabled = false;
}
function deactivate() {
btn.disabled = true;
}
function check() {
if (fname.value != '' && email.value != '' && email.checkValidity()) {
activate()
} else {
deactivate()
}
}
btn.addEventListener('click', function(e) {
alert('submit')
})
fname.addEventListener('input', check)
email.addEventListener('input', check)
}
<form>
<input type="text" name="" id="fname">
<input type="email" name="" id="email">
<input type="submit" id="submit-btn" value="Submit">
</form>

This is the simplest solution I can imagine:
myForm.oninput = () => {
btn.disabled = fname.value == '' || email.value == '' || !email.checkValidity();
}
<form id="myForm">
<input type="text" name="" id="fname">
<input type="email" name="" id="email">
<input type="submit" id="btn" value="Submit" disabled>
</form>
Personally, I prefer to use regex to check the e-mail, instead of checkValidity(). Something like this:
/^[\w\-\.\+]+\#[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/.test(email.value);

Submit HTML Form to firestore with Validation without a action [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 " onsubmit " Event Not Working Correctly

I am just practicing js. I am trying to make a very simple validation in form but it came with, as i was expecting, an error.
Here's my code :
var form = document.getElementById('form');
var name = document.getElementById('name');
var email = document.getElementById('email');
var msg = document.getElementById('message');
var error = document.getElementById('error');
function handlingForm() {
form.onsubmit = function(c)
{
if (name.value == "")
{
error.innerHTML = "Error Submiting Form !";
return false;
}
else
{
error.innerHTML = "You have successfuly submited the Form..! Congrats ;)";
return true; // ;) Just Kidding :D
}
};
}
window.onload = function(c)
{
handlingForm();
}
<!DOCTYPE html>
<html>
<head>
<title>jsForm</title>
<link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
<div id="container">
<form id="form">
<input type="text" placeholder="Name" id="name">
<input type="text" placeholder="Email" id="email">
<textarea rows="4" placeholder="Message" id="message"></textarea>
<input type="submit" value="Send" id="send">
<p id="error"></p>
</form>
</div>
<script src="script.js"></script>
</body>
</html>
The problem is that, it doesn't validate it. Every time it returns true on submitting but when i replace the " name.value" with "email.value" the code works. I don't know now what's the problem actually. If someone could help me..

It looks like the input with id name is not created in DOM by the time of JavaScript execution.
You can resolve that by putting the code in the window.onload code block or inside the form.onsubmit
var form = document.getElementById('form');
var email = document.getElementById('email');
var msg = document.getElementById('message');
var error = document.getElementById('error');
function handlingForm() {
form.onsubmit = function(c) {
var name = document.getElementById('name');
if (name.value == "") {
error.innerHTML = "Error Submiting Form !";
return false;
} else {
error.innerHTML = "You have successfuly submited the Form..! Congrats ;)";
return true; // ;) Just Kidding :D
}
};
};
handlingForm();
<div id="container">
<form id="form">
<input type="text" placeholder="Name" id="name">
<input type="text" placeholder="Email" id="email">
<textarea rows="4" placeholder="Message" id="message"></textarea>
<input type="submit" value="Send" id="send">
<p id="error"></p>
</form>
</div>

Your variable called name is a problem. It's not working because name is a predefined identifier in some implementations. Though it's not a reserved keyword, it's best practice to avoid using it as a variable name.
Rename it to name_ (or almost anything else) and it will work.

If name.value has no value, it is undefined. So undefined !== "", which is why it will never be true. Just do a null check for name.value. Also, you need to move name inside of that function since the first time it is called, value will always be undefined:
var form = document.getElementById('form');
var email = document.getElementById('email');
var msg = document.getElementById('message');
var error = document.getElementById('error');
function handlingForm() {
form.onsubmit = function(c)
{
var name = document.getElementById('name');
if (!name.value)
{
error.innerHTML = "Error Submiting Form !";
return false;
}
else
{
error.innerHTML = "You have successfuly submited the Form..! Congrats ;)";
return true; // ;) Just Kidding :D
}
};
}
window.onload = function(c)
{
handlingForm();
}
<!DOCTYPE html>
<html>
<head>
<title>jsForm</title>
<link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
<div id="container">
<form id="form">
<input type="text" placeholder="Name" id="name">
<input type="text" placeholder="Email" id="email">
<textarea rows="4" placeholder="Message" id="message"></textarea>
<input type="submit" value="Send" id="send">
<p id="error"></p>
</form>
</div>
<script src="script.js"></script>
</body>
</html>

Try this:
window.onload = handlingForm();
Why your function has c parameter?

This is due to a quirk of how global variables are handled in web pages. Each one is treated as a property of the window object, so when you assign to email, you're actually creating and assigning to window.email, and so on.
However, some properties of the window object already exist and have special meaning to the browser, such as window.location (the current URL) and window.name (used in cross-frame link targets).
To see it in practice, do this in the global scope (outside any function):
var location; // should be undefined, right?
alert(location); // but it's actually window.location
Because of the special meaning of window.name, anything you assign to it (or to global name) will be converted into a string. The element that you try to store becomes a string, and so no longer works as an element.
To fix it, simply move your code into a function, so that the variables are local and no longer have this strange behaviour. You can use your window.onload function for this.

stopping form submit if the validation fails.

I am validating the dates in below function. If the validation fails, then the form should not get submitted. I tried returning false in form onsubmit but it still gets submitted. However, Validation is working fine and getting the alert that I put in the function. Any help to stop submitting the form if validation fails.
<script>
function dateCheck()
{
start = document.getElementById('name3').value;
end = document.getElementById('name4').value;
compare(start, end);
document.getElementById('name4').focus();
}
function compare(sDate, eDate)
{
function parseDate(input) {
var parts = input.match(/(\d+)/g);
return new Date(parts[2], parts[0]-1, parts[1]); // months are 0-based
}
var parse_sDate = parseDate(sDate);
var parse_eDate = parseDate(eDate);
parse_sDate.setFullYear(parse_sDate.getFullYear() + 1);
if(parse_eDate >= parse_sDate)
{
alert("End date should not be greater than one year from start date");
return false;
}
return true;
}
</script>
</head>
<body>
<form onsubmit="return dateCheck()">
<table>
<tr>
<td><input type="text" name="soname3" id="name3" size="15" readonly="readonly">
<img src="../Image/cal.gif" id="" style="cursor: pointer;" onclick="javascript:NewCssCal('name3','MMddyyyy','dropdown',false,'12')" /></td>
<td><input type="text" name="soname4" id="name4" size="15" readonly="readonly">
<img src="../Image/cal.gif" id="" style="cursor: pointer;" onclick="javascript:NewCssCal('name4','MMddyyyy','dropdown',false,'12'); " /> </td>
</tr>
</table>
<input type="submit" value="Submit">
</form>

Just a comment:
If your listener passes a reference to the form, you can access the controls by name or ID:
<form onsubmit="return dateCheck(this)">
then:
function dateCheck(form) {
var start = form.name3.value;
...
}
Note that you should declare variables, otherwise they will become global at the point they are assigned to. Also, you should check the values in the controls before passing them to the compare function (and display a message asking the user to enter a valid value if they aren't).
function dateCheck(form) {
var start = form.name3.value;
var end = form.name4.value;
var valid = compare(start, end);
if (!valid) form.name4.focus();
return false;
}

I appreciate all contributions above. I have just applied the suggestions above to solve my challenge & it works fine. Keeping it simple I use the following:
<form id="newuser" action="newuser.php" onsubmit="return pswderr(this)">
For the button I have
<input id='submit' type="submit" value="Login" onClick="return pswderr();">
My script is:
<script>
function pswderr() {
var pswd1 = document.getElementById("newuserpswd").value;
var pswd2 = document.getElementById("rptpswd").value;
if (pswd1 !== pswd2) {
document.getElementById("alarm").innerHTML = "Password and password
verification do not match. Retry";
return false;
} else {document.getElementById("alarm").innerHTML = "";
return true;
}
}
</script>

use return on the onclick attribute in the form tag attribute onsubmit="return validateForm()" , if you return false in your validation function in javascript if the input is incorrect then you have to add return to your onclick attribute in order for it to execute .Hope it helped someone!
<script>
function validateForm(){
var validation = false;
var phonenumber = document.forms["enqueryForm"]["phonenumber"].value;
if(phonenumber != 11) {
alert("phonenumber is incorrect");
//e.preventDefault();
return false;
}
}
</script>
<form class="form-style-5" action="BookingForm.php" method="post" id="bookingForm" onsubmit="return validateForm()" name="enqueryForm">
<input type="tel" name="phonenumber" placeholder="your no.">
<input type="submit" name="submit" value="submit">
</form>

return is not going to stop the form from submit if its called in a subfunction e.g. compare(sDate, eDate)
so change your function to this
function dateCheck(e){
var start = document.getElementById('name3').value;
var end = document.getElementById('name4').value;
if(compare(start, end)) {
// no error submit i guess
// return true ?
} else {
// error with date compare
return false;
}
end.focus();
}

In my case i used pattern in input field and also gave maxlength.
What worked with me was, remove Length attribute from input field

you can achieve the same thing using jQuery Form Plugin.
$(document).ready(function() {
$('#your_form_id').ajaxForm( { beforeSubmit: dateCheck } );
});

- I hope this will help you : Just write this code on your Html/jsp page
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
- **Don't forget to add this on your html page**
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script type='text/javascript'>
$(document).ready(function() {
//option A
$("regF").submit(function(e) { //regF is form id
alert('submit intercepted');
e.preventDefault(e);
});
});
</script>
</html>