RegEx for extracting url parameters

Question

I need to extract url parameters from the following string

?theAccount=someData&theToken=sometoken&mediaId=someid

so I want someData sometoken someid

here is the function I am using

function getParams( name ) {
            var str = window.location.search;
            var r = new RegExp("/(^\?|&+)"+name+"(\=)/");
            var result =  r.exec(str);
            if (r) { return result; }
            return "";

        }

called like so getParams(theAccount);

But it's not working and keeps "invalid regular expression". Any help is much appreciated.