Question

129

Adding/Modify query string / GET variables in a url with javascript

rated 0 times [ 131] [ 2] / answers: 1 / hits: 16464 / 13 Years ago, mon, october 3, 2011, 12:00:00

So I am wanting to replace GET variable values in a url and if the variable does not exist, then add it to the url.

EDIT: I am doing this to a elements href not the pages current location..

I am not good with javascript but I do know how to use jQuery quite well and the basics of javascript. I do know how to write regex but not how to use the javascript syntax of regex and what functions to use it with.

Here is what I have so far and it does have an error on line 3: See it on jsfiddle(or below): http://jsfiddle.net/MadLittleMods/C93mD/

function addParameter(url, param, value) {

    var pattern = new RegExp(param + '=(.*?);', 'gi');

    return url.replace(pattern, param + '=' + value + ';');



    alert(url);

}

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adriannemyiag

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3 Years ago

answered 13 Years ago myrap · Accepted Answer

No need to use jQuery on this one. Regular Expressions and string functions are sufficient. See my commented code below:

function addParameter(url, param, value) {

    // Using a positive lookahead (?==) to find the

    // given parameter, preceded by a ? or &, and followed

    // by a = with a value after than (using a non-greedy selector)

    // and then followed by a & or the end of the string

    var val = new RegExp('(\?|\&)' + param + '=.*?(?=(&|$))'),

        parts = url.toString().split('#'),

        url = parts[0],

        hash = parts[1]

        qstring = /?.+$/,

        newURL = url;



    // Check if the parameter exists

    if (val.test(url))

    {

        // if it does, replace it, using the captured group

        // to determine & or ? at the beginning

        newURL = url.replace(val, '$1' + param + '=' + value);

    }

    else if (qstring.test(url))

    {

        // otherwise, if there is a query string at all

        // add the param to the end of it

        newURL = url + '&' + param + '=' + value;

    }

    else

    {

        // if there's no query string, add one

        newURL = url + '?' + param + '=' + value;

    }



    if (hash)

    {

        newURL += '#' + hash;

    }



    return newURL;

}

And here is the Fiddle

Update:

The code now handles the case where there is a hash on the URL.

Edit

Missed a case! The code now checks to see if there is a query string at all.