How to prevent ENTER keypress to submit a web form?

How do you prevent an ENTER key press from submitting a form in a web-based application?

[revision 2012, no inline handler, preserve textarea enter handling]

function checkEnter(e){
 e = e || event;
 var txtArea = /textarea/i.test((e.target || e.srcElement).tagName);
 return txtArea || (e.keyCode || e.which || e.charCode || 0) !== 13;
}

Now you can define a keypress handler on the form:
<form [...] onkeypress="return checkEnter(event)">

document.querySelector('form').onkeypress = checkEnter;

Here is a jQuery handler that can be used to stop enter submits, and also stop backspace key -> back. The (keyCode: selectorString) pairs in the "keyStop" object are used to match nodes that shouldn't fire their default action.

Remember that the web should be an accessible place, and this is breaking keyboard users' expectations. That said, in my case the web application I am working on doesn't like the back button anyway, so disabling its key shortcut is OK. The "should enter -> submit" discussion is important, but not related to the actual question asked.

Here is the code, up to you to think about accessibility and why you would actually want to do this!

$(function(){
 var keyStop = {
   8: ":not(input:text, textarea, input:file, input:password)", // stop backspace = back
   13: "input:text, input:password", // stop enter = submit 

   end: null
 };
 $(document).bind("keydown", function(event){
  var selector = keyStop[event.which];

  if(selector !== undefined && $(event.target).is(selector)) {
      event.preventDefault(); //stop event
  }
  return true;
 });
});

Simply return false from the onsubmit handler

<form onsubmit="return false;">

or if you want a handler in the middle

<script>
var submitHandler = function() {
  // do stuff
  return false;
}
</script>
<form onsubmit="return submitHandler()">