How to prevent document.forms[0].submit() from submitting a form?

Question

This is basically my form:

<form method="post" action="" onsubmit="checkallfields(); event.preventDefault();">
  <!-- My Stuff -->
</form>

And it is the first form on my page. I have client-side field validation, which obviously is stored in the function checkallfields() . But the problem is, that the user can be very naughty and open up the console and type document.forms[0].submit() , and then the form will still submit.

How do I prevent this?

Answer 1

You can't prevent it. That is why you need to do serverside validation and that is why you should ALWAYS do serverside validation. The clientside can not be trusted and I do not even need your webpage to submit to your server.

Answer 2

I thought about the problem, and got my own answer. Tested it in Google Chrome.

var i = document.forms.length;
while (i--) {
  document.forms[i].submit = function () {
    return false;
  }
}

Does it work for you guys? You can check here: http://jsfiddle.net/think123/ZRuYw/

Answer 3

Just set that function on the document to false.

document.forms[0].submit = function () {
  return false;
}