Redeclared javascript global variable overrides old value in IE
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by Yousuf Haider
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Published on 2010-04-14T05:06:25Z
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2010/04/14
5:23 UTC
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(creating a separate question after comments on this: http://stackoverflow.com/questions/2634410/javascript-redeclared-global-variable-overrides-old-value)
I am creating a globally scoped variable using the square bracket notation and assigning it a value inside an external js file.
In another js file I declare a var with the same name as the one I just created above. Note I am not assigning a value. Since this is a redeclaration of the same variable the old value should not be overriden as described here: http://www.w3schools.com/js/js_variables.asp
Create 2 javascript files with the following content : Script1
//create global variable with square bracket notation
window['y'] = 'old';
Script2
//redeclaration of the same variable
var y;
if (!y) y = 'new';
alert(y); //shows New instead of Old in IE
Include these 2 files in your html file
<html>
<head></head>
<body>
<script type="text/javascript" src="my.js"></script>
<script type="text/javascript" src="my2.js"></script>
</body>
</html>
Opening this page in Firefox and Chrome alerts 'old' which is the expected behavior. However in IE 8 the page will actually alert 'new'
Any ideas on why this happens on IE ?
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