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The shExpMatch function in .pac files does not support regular expressions

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Summary

When you use the shExpMatch function in .pac files, advanced regular expression syntax does not work in Internet Explorer.

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More information

The shExpMatch function is used in .pac files to match the current URL against any shell expression. In addition, shExpMatch is usually used to decide which proxy to use depending on the URL that is entered. In Internet Explorer, the support for shell expressions is limited to "?" and "*" in the expressions. This is by design.

Because .pac files support the entire JavaScript language, you can use a regular expression object and the test method to test a string against a regular expression. The following code sample illustrates the use of the regular expression object in a .pac file: 
function FindProxyForURL(url, host)
{
// For instance, if the server has 4 alphabetic characters, 
// such as "MSDN", route it through a specific proxy: 

var regexpr = /[a-zA-Z]{4}.microsoft.com/;
if(regexpr.test(host))
    return "PROXY w3proxy:8080; DIRECT";

// Or else connect directly:
return "DIRECT";
}

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References

For more information about the .pac file syntax, visit the following Netscape Web site:
http://wp.netscape.com/eng/mozilla/2.0/relnotes/demo/proxy-live.html
For more information on regular expressions, visit the following Mozilla Web site:
http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Guide:Regular_Expressions
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Properties

Retired KB Content Disclaimer
This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.

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Keywords: KB274204, kbscript, kbinfo

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Article Info
Article ID : 274204
Revision : 4
Created on : 7/5/2007
Published on : 7/5/2007
Exists online : False
Views : 1125