Safari and Chrome doesn't evaluate dynamically added <script> tag at page load
Question
I am writing small JavaScript code which will load external js files at html page loading.
I tested 2 ways.
Case 1: Used document.write to add <script> tag. It worked for all browsers (IE, FF, Safari, Chrome, Opera).
Case 2: Used DOMElement.appendChild to add <script> tag to the <haed> element.
Only worked for IE, FF, and Opera. Did NOT work for Safari and Chrome.
In both cases, I expected new <script> tag is being inserted before <head> closing tag. So the new <script> tag is evaluated before processing <body>, and by the time window.onload is called, "success" variable should be true.
But it wasn't for Safari and Chrome.
Can anyone tell if this should or shouldn't work? Thank you.
<html>
<head>
<title>JavaScript loading test</title>
<script type="text/javascript">
var success = false;
window.onload = function()
{
document.getElementById("result").innerHTML = success? "OK": "ERROR!";
}
// TEST CASE 1.
// Works for all browsers.
document.write('<script type="text/javascript" src="foo.js"></' + 'script>');
// TEST CASE 2.
// Only works for Opera, FireFox, Opera.
// var scriptElem = document.createElement("script");
// scriptElem.setAttribute("type", "text/javascript");
// scriptElem.setAttribute("src", "foo.js");
// var headElem = document.getElementsByTagName("head")[0];
// headElem.appendChild(scriptElem);
</script>
<!-- expected new scrip tag being inserted here. -->
</head>
<body>
Testing...<br/>
<span id="result"></span>
</body>
</html>
"foo.js" is just one line of code.
success = true;
2 answers
solution1
4 2010-02-06 11:43:35
Try this instead:
var s = document.createElement('SCRIPT');
s.charset = 'UTF-8';
s.src ='foo.js';
document.getElementsByTagName('HEAD')[0].appendChild(s);
But place this in a SCRIPT tag at the beginning of the BODY tag
solution2
1 2010-02-06 09:23:22
At the time when your javascript is evaluated, the DOM isn't fully built, the head element is not even finished. You normally cannot access or manipulate the DOM ( getElementsByTagName and appendChild , etc. ) before the HTML page is fully loaded.
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