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How to fire "onload" event on document in IE

Answer 1

A:

The load event will fire when the document (including external resources such as images) has fully loaded, and not before.

What results are you getting from your attempts to fire readystatechange? Does the readyState value actually change at all? Whether or not, that's not of much use either: either you fire the event with a readyState that hasn't changed, or you do so with a readyState that isn't a valid reflection of the state of the document.

NickFitz 2009-12-09 16:27:18

@NickFitz Thanks for the answer. I am not trying to change the value of document.readyState, which remains 'complete' before (because I have a wait until readyState becomes 'complete') and after my test. Please keep in mind that this code is written for unit tests.

Eric Bréchemier 2009-12-09 16:35:11

@NickFitz: Eric is just trying to simulate the real-world `load` event for local unit tests.

Crescent Fresh 2009-12-09 16:41:28

If it's for a unit test then you shouldn't need to fire any events at all. Simply create a mock event object with known values and call the event handler directly, then check that it produced the correct results for those values. Otherwise it's not a unit test, it's an integration test: you are testing how the code integrates with the browser's internal event handling mechanisms.

NickFitz 2009-12-10 11:29:59

@NickFitz except I am not unit-testing the event handlers :) I am writing unit tests for a method that replaces and filters the addEventListener and attachEvent on window and document.

Eric Bréchemier 2009-12-10 16:28:55

Answer 2

+2 A:

According to this page at MSDN, there's no onload event for document.

You want either window.onload or document.body.onload. These are identical in IE: for historical reasons, <body onload="..."> actually sets window.onload, so MS decided to make document.body.onload an alias of window.onload.

The problem with this is - as Eric mentioned in the comments - that there doesn't seem to be a way to manually fire window events, which means that there might not be a solution for Eric's problem.

Christoph 2009-12-09 16:28:19

@Christoph: good point, already mentioned by Crescent Fresh: I should fire the event on document.body instead. Interesting comment on window.onload but not so helpful since window has no fireEvent method.

Eric Bréchemier 2009-12-09 16:38:00

@Christoph thanks for editing your answer. I'll accept it as a conclusion to this interesting discussion.

Eric Bréchemier 2009-12-09 17:41:50

Answer 3

+1 A:

For some reason, it appears that IE overrides the onload property of window with an empty object after the DOM is loaded. At least that is the case when you try to access it from within any event handler of a DOM element...

<!DOCTYPE html>
<html>
  <head>
    <title>Test by Josh</title>
    <script type="text/javascript">
      window.onload = function() {
        alert("Test");
      }
      alert(typeof window.onload);
    </script>
  </head>
  <body>
    <h1 onclick="alert(typeof window.onload);">Test</h1>
  </body>
</html>

In this situation, you'll see that window.onload is recognized as a function initially, then you see the "Test" alert. When you click on the heading, you'll see that window.onload is now an object. I tried iterating through the properties of the object, but it's empty. This is not cool.

One lame workaround is to grab the function in the accessible scope and assign it to a different property that you can fire at your convenience...

<!DOCTYPE html>
<html>
  <head>
    <title>Test by Josh</title>
    <script type="text/javascript">
      window.onload = function() {
        alert("Test");
      }         
    </script>
  </head>
  <body>
    <h1 onclick="window.onloadfix()">Test</h1>
    <!-- Could potentially be injected via server-side include if needed -->
    <script type="text/javascript">
      window.onloadfix = function() {
        window.onload();
      }
    </script>
  </body>
</html>

I can't think of any other way to address this issue right now.

Josh Stodola 2009-12-09 17:46:04

@Josh Stodola interesting... I discovered today that document.attachEvent is not a function in IE: you can call it of course, but (typeof document.attachEvent) returns "object" and both document.attachEvent.call and document.attachEvent.apply are undefined... this browser will never stop to surprise me.

Eric Bréchemier 2009-12-09 21:18:18

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