Check cookie value

[agibsonsw]

Hello.
I have the following JS code to check if a cookie name exists using a regular expression:

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var regX = new RegExp("\\b" + cookieName + "=([^;]*)");
var found = regX.exec(document.cookie);

There must be a similar expression that I could use to check if a cookie value exists?

Does someone have something similar? Or perhaps if you could describe the format of a cookie I could work out what sequence of characters I should be looking for to check for a value.

(I've found lots of examples that split the cookie and have used one to check the value, but this seems quite messy when a regular expression should be able to do the same thing.)

Thanks, Andy.

[agibsonsw]

Hello.

I was making some progress with

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var regX = new RegExp("(=" + cookieValue + ";)");

but I might have to revert to the full search based on splitting the cookie.

The problem is that the cookie name/values are escaped/encoded and the symbols used have a different meaning to RegExp. Never mind, Andy.

[agibsonsw]

I do like to answer my own questions occasionally! To check for an escaped or encoded cookie name or value requires the escaped name/value to also be escaped for use within a regular expression. The follow helper function and two functions will 'quickly' check for the existence of either a cookie name or value (case insensitive).

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// Escapes characters for use with a regular expression
String.prototype.EscapeR = function () { return this.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&"); }

function Name_Exists ( cookie_name )
    {
        if (document.cookie.length == 0) return false;
        var testName = escape(cookie_name);
        testName = testName.EscapeR();
        var myReg = new RegExp('(^|;) ?' + testName + '=([^;]*)(;|$)','gi');
        return myReg.test(document.cookie);
    }
    function Value_Exists ( cookie_value )
    {
        if (document.cookie.length == 0) return false;
        var testName = encodeURI(cookie_value);     // or escape(cookie_value) if appropriate
        testName = testName.EscapeR();
        var myReg = new RegExp('(=)' + testName + '(;|$)','gi');
        return myReg.test(document.cookie);
    }

I wanted to use regular expressions rather than having to split the cookie and loop through it's array each time.

(I haven't tested them for hours on end but they appear to be doing a good job.)