Execute javascript code straight before page submit

Question

There are a few similar questions to this but none quite the same.

I want to know if there is an event that can be used to execute some JS before a page is submitting (i.e. POSTed).

Answer 1

Something like this?

<form onsubmit="do_something()">

function do_something(){
   // Do your stuff here
}

If you put return like the code below, you can prevent the form submission by returning false from the do_something() function.

<form onsubmit="return do_something()">

function do_something(){
   // Do your stuff here
   return true; // submit the form

   return false; // don't submit the form
}

Answer 2

If you are working with the form, you can use onsubmit event.

Using jQuery you can do that with

$('#myform').submit(function() {
  // your code here
});

Answer 3

You can bind an event handler to the submit event (following code assumes you have an id on your form):

document.getElementById("someForm").onsubmit = function() {
    //Do stuff
};

Answer 4

Yes, you can use on the onsubmit event on your form.

In pure HTML (without jQuery), you can use:

<form onSubmit="mySubmitFunction()">
   ...
</form>

More details here: https://www.w3schools.com/jsref/event_onsubmit.asp

Answer 5

The following code will abort the submission from the window level, which will not submit the form.

window.onsubmit = function() { alert('aborting submit'); return false; };

Tested with IE11, so it should work for some legacy applications without jQuery.