Change form's onsubmit function

Question

I want to perform validation before any other onsubmit actions. Unfortunately, I have no control over the value of the onsubmit attribute on the form. So for example:

<form id="myForm" onsubmit="return stuffICantChange()"></form>

I've tried the following code, and several other methods, with no luck:

$("#myForm").onsubmit = function() {
    console.log("hi");
}

Any help is appreciated, thanks.

If this is a duplicate, please let me know before marking it as such so that I can refute the claim if necessary.

EDIT:

My code as requested:

<form id="form_ContactUs1" name="form" method="post" action="index.php" onsubmit="return  Validator1(this) &amp;&amp; ajaxFormSubmit(this); return false">
<div class="form">

    <div class="form-staticText">
        <p>We look forward to hearing from you! Please fill out the form below and we will get back with you as soon as possible.</p>
    </div>


    <div class="form-group">
        <input class="form-control" placeholder="Name" id="IDFormField1_Name_0" name="formField_Name" value="" size="25" required="" type="text">
        <span class="form-control-feedback"></span>
    </div>


    <div class="form-group">
        <input class="form-control" placeholder="Email" id="IDFormField1_Email_0" name="formField_Email" value="" size="25" required="" type="email">
        <span class="form-control-feedback"></span>
    </div>


    <div class="form-group">
        <input class="form-control bfh-phone" data-format="ddd ddd-dddd" placeholder="Phone" id="IDFormField1_Phone_0" name="formField_Phone" value="" size="25" type="tel">
        <span class="form-control-feedback"></span>
    </div>


    <div class="form-group">
        <textarea class="form-control" placeholder="Comments" name="formField_Comments" id="IDFormField1_Comments_0" cols="60" rows="5" required=""></textarea>
        <span class="form-control-feedback"></span>
    </div>



    <div class="row submit-section">

        <input name="submit" class="btn btn-success submit-button" value="Submit" type="submit">
    </div>
</div>

$( "form" ).each(function() {

    console.log( $(this)[0] );
    sCurrentOnSubmit = $(this)[0].onsubmit;
    $(this)[0].onsubmit = null;
    console.log( $(this)[0] );

    $( this )[0].onsubmit( function() {
        console.log( 'test' );

    });

});

Answer 1

You should be able to add unobtrusively another onsubmit function to #myForm , in addition to the function which already executes:

function myFunction() {
    ...
}

var myForm = document.getElementById('myForm');
myForm.addEventListener('submit',myFunction,false);

Answer 2

Try

$("#myForm").submit(function(){
   .. Your stuff..
   console.log("submit");
   return false;
});

This will trigger everytime the form is submitted then the end return false stops the forms default actions from continuing.

Answer 3

Try this, it is plain Javascript:

function overrideFunction(){
  console.log('Overrided!');
}
var form;
form = document.querySelector('#myForm');
form.setAttribute('onsubmit','overrideFunction()');

Regards.

Answer 4

You should trigger a change event on every field in the form to check on validation.

$('input').on('change', function(e) {
   if($(this).val() == '') {
        console.log('empty');
   } 
});

This wil help the user mutch faster then waiting for the submit.

You could also try a click event before the submit.

$('#formsubmitbutton').on('click', function(e) {
   //your before submit logic

   $('#form').trigger('customSubmit'); 
});

$('#form').on('customSubmit', function(e) {
  //your normal submit
});

Answer 5

Try this code:

$("#myForm").on('submit',function() {
    console.log("hi");
});

Answer 6

Stumbling across this post and putting together other javascript ways to modify html, I thought I would add this to the pile as what I consider a simpler solution that's more straight forward.

 document.getElementById("yourFormID").setAttribute("onsubmit", "yourFunction('text','" + Variable + "');");

 <form id="yourFormID" onsubmit="">.... </form>