21 lines
1.3 KiB
JavaScript
21 lines
1.3 KiB
JavaScript
// checks whether or not the url is external to the local site.
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// generously provided by StackOverflow: http://stackoverflow.com/questions/6238351/fastest-way-to-detect-external-urls
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function isExternal(url) {
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// parse the url into protocol, host, path, query, and fragment. More information can be found here: http://tools.ietf.org/html/rfc3986#appendix-B
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var match = url.match(/^([^:\/?#]+:)?(?:\/\/([^\/?#]*))?([^?#]+)?(\?[^#]*)?(#.*)?/);
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// match[1] matches a protocol if one exists in the url
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// if the protocol in the url does not match the protocol in the window's location, this url is considered external
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if (typeof match[1] === "string" &&
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match[1].length > 0
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&& match[1].toLowerCase() !== location.protocol)
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return true;
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// match[2] matches the host if one exists in the url
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// if the host in the url does not match the host of the window location, this url is considered external
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if (typeof match[2] === "string" &&
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match[2].length > 0 &&
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// this regex removes the port number if it patches the current location's protocol
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match[2].replace(new RegExp(":("+{"http:":80,"https:":443}[location.protocol]+")?$"), "") !== location.host)
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return true;
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return false;
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}
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