JavaScript function to parse the query string part of a URL.

/**
 * Parses the query string part of a URL.
 *
 * This method returns a simple key/value map. If there are duplicate keys the
 * latest value is returned.
 *
 * @param {string} queryString
 * @return {!Object<string, string>}
 */
function parseQueryString(queryString) {
    var params = {};
    if (!queryString) {
        return params;
    }
    if (queryString.startsWith('?') || queryString.startsWith('#')) {
        queryString = queryString.substr(1);
    }
    var pairs = queryString.split('&');
    for (var i = 0; i < pairs.length; i += 1) {
        var pair = pairs[i];
        var eqIndex = pair.indexOf('=');
        var _name;
        var value;
        if (eqIndex != -1) {
            _name = decodeURIComponent(pair.substring(0, eqIndex)).trim();
            value = decodeURIComponent(pair.substring(eqIndex + 1)).trim();
        }
        else {
            _name = decodeURIComponent(pair).trim();
            value = '';
        }
        if (_name) {
            params[_name] = value;
        }
    }
    return params;
}