I am having trouble with the window.onload
and document.onload
events. Everything I read tells me these will not trigger until the DOM is fully loaded with all its resources, it seems like this isn't happening for me:
I tried the following simple page in Chrome 4.1.249.1036 (41514) and IE 8.0.7600.16385 with the same result: both displayed the message "It failed!", indicating that myParagraph
is not loaded (and so the DOM seems incomplete).
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<script type="text/javascript">
window.onload = doThis();
// document.onload gives the same result
function doThis() {
if (document.getElementById("myParagraph")) {
alert("It worked!");
} else {
alert("It failed!");
}
}
</script>
</head>
<body>
<p id="myParagraph">Nothing is here.</p>
</body>
</html>
I am using more complex scripts than this, in an external .js file, but this illustrates the problem. I can get it working by having window.onload
set a timer for half a second to run doThis()
, but this seems like an inelegant solution, and doesn't answer the question of why window.onload
doesn't seem to do what everyone says it does. Another solution would be to set a timer that will check if the DOM is loaded, and if not it will just call itself half a second later (so it will keep checking until the DOM is loaded), but this seems overly complex to me.
Is there a more appropriate event to use?
Just use window.onload = doThis;
instead of window.onload = doThis();
At the time window is loaded the body isn't still loaded therefore you should correct your code in the following manner:
<script type="text/javascript">
window.onload = function(){
window.document.body.onload = doThis; // note removed parentheses
};
function doThis() {
if (document.getElementById("myParagraph")) {
alert("It worked!");
} else {
alert("It failed!");
}
}
</script>
Tested to work in FF/IE/Chrome, although thinking about handling document.onload
too.
As already mentioned, using js-frameworks will be a far better idea.
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