Snippet to parse URL query strings, returning an object whose keys are parameter names and whose values are an array of the parameters themselves

gistfile1.txt

// via http://codereview.stackexchange.com/questions/9574/faster-and-cleaner-way-to-parse-parameters-from-url-in-javascript-jquery

function parseQueryString() {
    var query = (window.location.search || '?').substr(1),
        map   = {};
    query.replace(/([^&=]+)=?([^&]*)(?:&+|$)/g, function(match, key, value) {
        (map[key] = map[key] || []).push(value);
    });
    return map;
}

// Note that I'm not returning exactly the same data structure you are, but that's on purpose. Mashing an object and array together will fail if the query string has keys like "length" or "push".

// This function will also work with parameters that are re-used, parameters with empty values, parameters without an equals sign, and malformed urls. If you know you won't need to parse query strings where the same key is used multiple times, you could replace line 5 with map[key] = value;.