Multiple form submission is one of the issues that a webmaster face during his development.So instead of writing a hardcore code in the server side.We can just validate a multiple submission using simple client side Jquery.
Consider we have this HTML form in our code:

<form id="check" action="someUrl.php" method="get">
    <input name="username" />
    <!-- some more form fields -->
    <input id="submit" type="submit" />
</form>

Here is a jQuery code that disables submit button on form submission:

$('#check').submit(function(){
    $('input[type=submit]', this).attr('disabled', 'disabled');
});

The above jQuery code binds a submit event to our #check form, then finds its submit button and disables it.

Disable submit button on form submission for all forms on your page.

// Find ALL <form> tags on your page
$('form').submit(function(){
    // On submit disable its submit button
    $('input[type=submit]', this).attr('disabled', 'disabled');
});

Thanks HOW TO JQUERY

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