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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 );
}

Can't submit form through javascript to php

I have a form in html which I want to run verification in Javascript first before POST ing to PHP. However the link up to the PHP section does not seem to be working despite the fact that I have assigned names to each input tag and specified an action attribute in the form tag.
Here is the HTML code for the form:
<form id="signupform" action="signupform.php" method="post">
<input type="text" name="Email" placeholder="Email Address" class="signupinput" id="email" />
<br />
<input type="password" name="Password" placeholder="Password" class="signupinput" id="passwordone" />
<br />
<input type="password" placeholder="Repeat Password" class="signupinput" id="passwordtwo" />
<br />
<input type="button" value="Sign Up" class="signupinput" onClick="verifypass()" id="submit" />
</form>
The button calls the javascript function which I use to verify the values of my form before sending to php:
function verifypass() {
var form = document.getElementById("signupform");
var email = document.getElementById("email").value;
var password1 = document.getElementById("passwordone").value;
var password2 = document.getElementById("passwordtwo").value;
var emailcode = /^(([^<>()\[\]\\.,;:\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,}))$/;
if (emailcode.test(email)) {
if (password1.length > 6) {
if (password1 == password2) {
form.submit(); //this statement does not execute
} else {
$("#passwordone").notify("Passwords do not match!", {
position: "right"
})
}
} else {
$("#passwordone").notify("Password is too short!", {
position: "right"
})
}
} else {
$("#email").notify("The email address you have entered is invalid.", {
position: "right"
})
}
}

For some reason, some JavaScript implementations mix up HTML element IDs and code. If you use a different ID for your submit button it will work (id="somethingelse" instead of id="submit"):
<input type="button" value="Sign Up" class="signupinput" onClick="verifypass()" id="somethingelse" />
(I think id="submit" has the effect that the submit method is overwritten on the form node, using the button node. I never figured out why, perhaps to allow shortcuts like form.buttonid.value etc. I just avoid using possible method names as IDs.)

I'm not sure why that's not working, but you get around having to call form.submit(); if you use a <input type="submit"/> instead of <input type="button"/> and then use the onsubmit event instead of onclick. That way, IIRC, all you have to do is return true or false.

I think it would be better if you do it real time, for send error when the user leave each input. For example, there is an input, where you set the email address. When the onfocusout event occured in Javascript you can add an eventlistener which is call a checker function to the email input.
There is a quick example for handling form inputs. (Code below)
It is not protect you against the serious attacks, because in a perfect system you have to check on the both side.
Description for the Javascript example:
There is two input email, and password and there is a hidden button which is shown if everything is correct.
The email check and the password check functions are checking the input field values and if it isn't 3 mark length then show error for user.
The showIt funciton get a boolean if it is true it show the button to submit.
The last function is iterate through the fields object where we store the input fields status, and if there is a false it return false else its true. This is the boolean what the showIt function get.
Hope it is understandable.
<style>
#send {
display: none;
}
</style>
<form>
<input type="text" id="email"/>
<input type="password" id="password"/>
<button id="send" type="submit">Send</button>
</form>
<div id="error"></div>
<script>
var fields = {
email: false,
password: false
};
var email = document.getElementById("email");
email.addEventListener("focusout", emailCheck, false);
var password = document.getElementById("password");
password.addEventListener("focusout", passwordCheck, false);
function emailCheck(){
if(email.value.length < 3) {
document.getElementById("error").innerHTML = "Bad Email";
fields.email = false;
} else {
fields.email = true;
document.getElementById("error").innerHTML = "";
}
show = checkFields();
console.log("asdasd"+show);
showIt(show);
}
function passwordCheck(){
if(password.value.length < 3) {
document.getElementById("error").innerHTML = "Bad Password";
fields.password = false;
} else {
fields.password = true;
document.getElementById("error").innerHTML = "";
}
show = checkFields();
console.log(show);
showIt(show);
}
function showIt(show) {
if (show) {
document.getElementById("send").style.display = "block";
} else {
document.getElementById("send").style.display = "none";
}
}
function checkFields(){
isFalse = Object.keys(fields).map(function(objectKey, index) {
if (fields[objectKey] === false) {
return false;
}
});
console.log(isFalse);
if (isFalse.indexOf(false) >= 0) {
return false;
}
return true;
}
</script>

jQuery .ready is not working

Can anyone tell me why this code wouldn't work? I have an input and I'm trying to check weather or not the input is "start". So I do... how ever nothing is working - not even the .ready but I'm new so I have no idea what the problem is.
HTML
<form id="inputForm" onsubmit="return false;">
<input id="input" type="text" size="30" autofocus="autofocus" maxlength="100" autocomplete="off"/>
</form>
JS:
var input = "";
$(document).ready(function() {
$("#inputForm").submit(function() {
input = $("#input").val().toUpperCase();
if (input === "START") {
alert("worked");
}
$("#command_input").val("");
})
});

I suspect that you haven't included jQuery in your webpage. You can import it by adding
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.2/jquery.min.js"></script>
Before the script tag for your code. (https://code.jquery.com/jquery has more jQuery CDNs too)
You really don't need jQuery to do this though. Here's the plain JS equivalent code working here:
var input = "";
document.body.onload = function() {
document.getElementById("inputForm").addEventListener("submit", function() {
input = document.getElementById("input").value.toUpperCase();
if (input === "START") {
alert("worked");
}
document.getElementById("command_input").value = "";
});
};

After looking at the code here: https://jsfiddle.net/cu7tn64o/1/
It seems to work fine! As the other commenters have mentioned, this is likely because you have not included jQuery in your html file like so:
<script src="https://code.jquery.com/jquery-2.2.3.min.js"></script>
https://code.jquery.com/

First include the jquery file using script tag in your html file.
Submit the form using jquery or in the below case I have submitted using a button. Onsubmit the value is taken from the input field and compared.
var input = "";
$(document).ready(function() {
$("#inputForm").submit(function() {
input = $("#input-value").val().toUpperCase();
if (input === "START") {
alert("worked");
}
else
{
alert("sorry");
}
$("#command_input").val("");
})
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form id="inputForm" onsubmit="return false;">
<input id="input-value" type="text" size="30" autofocus="autofocus" maxlength="100" autocomplete="off"/>
<input type="submit" name="submit" value="submit" />
</form>

If you return false from the event handler, things ought to work.
var input = "";
$(document).ready(function() {
$("#inputForm").submit(function() {
input = $("#input-value").val().toUpperCase();
if (input === "START") {
alert("worked");
} else {
alert("sorry");
}
$("#command_input").val("");
// You have to return false HERE to prevent the default action of a
// form -- send a request to a server, that is
return false;
});
});

How can I submit my form if all the validation is correct?

I have just finished getting my validation to work. When I press submit an error box appears with the error relating to the field (e.g special chars used). When all the fields are correct I now need to submit the form. How can I do this? When I press submit nothing happens.
$('button#form-submit').click(function() {
$.each($("form#all-details input,form#all-details select"),function(a,b){
if (typeof $(this).attr("data-type") != "undefined") {
if ($(this).val()=="") {
dialogWarning('Failure with form submit', '<p>Field <b>"'+$(this).prop("placeholder")+'"</b> must be populated</p>');
return false;
};
if ($(this).attr("data-type")=="text") {
if (/^[a-z0-9 ]+$/i.test($(this).val())===false) {
dialogWarning('Failure with form submit', '<p>Please do not use special characters in field <b>"'+$(this).prop("placeholder")+'"</b></p>');
return false;
};
} else if ($(this).attr("data-type")=="number") {
if ($.isNumeric($(this).val())===false){
dialogWarning('Failure with form submit', '<p>Field <b>"'+$(this).prop("placeholder")+'"</b> must be a number only</p>');
return false;
}
}
};
});
/* Submit form */
});
<form id="all-details" onSubmit="return false;" action="add_Consignee.php" method="POST">
Consignee:</br>
<input type="text" name="Consignee" id="text" data-type="text" placeholder="Consignee"></br>
Name:</br>
<input type="text" name="Name" data-type="text" placeholder="Name" ></br>
<input type="number" name="Forwarder_Contact_Number" data-type="number" placeholder="Forwarder Contact Number"></br>
Any Special Requirements?</br>
<input type="text" name="Special_Req" data-type="text" placeholder="Any Special Requirements"></br> </br>
<button id="form-submit">Submit</button>
</form>

I'd do like this:
$('button#form-submit').click(function() {
var _errors = [];
$.each($("form#all-details input,form#all-details select"),function(a,b){
if (typeof $(this).attr("data-type") != "undefined") {
if ($(this).val()=="") {
_errors.push('<p>Field <b>"'+$(this).prop("placeholder")+'"</b> must be populated</p>');
};
if ($(this).attr("data-type")=="text") {
if (/^[a-z0-9 ]+$/i.test($(this).val())===false) {
_errors.push('<p>Please do not use special characters in field <b>"'+$(this).prop("placeholder")+'"</b></p>');
_errors++;
};
} else if ($(this).attr("data-type")=="number") {
if ($.isNumeric($(this).val())===false){
_errors.push('<p>Field <b>"'+$(this).prop("placeholder")+'"</b> must be a number only</p>');
_errors++;
}
}
};
});
if (_errors.length > 0) {
dialogWarning('Failure with form submit', _errors.join(' ');
return false;
} else {
$(this).submit();
}
/* Submit form */
});
This way it'll treat multiple errors at once, and you'll have more control over the click event.

This should work if your button has type="submit" added to it.

Put your validation inside a function, eg
function validate() {
// validation code
}
Then call it in your form: onSubmit="validate()"

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>