queryParam.js

function queryParam(key) {
    // if it doesn't contain a question mark, return undefined
    var qmPos = window.location.href.indexOf("?");
    if(qmPos === -1) {
        return undefined;
    }

    // if it doesn't contain our key, also return undefined
    var keyPos = window.location.href.indexOf(key+"=", qmPos);
    if(keyPos === -1) {
        return undefined;
    }


    var ampPos = window.location.href.indexOf("&", keyPos);
    
    return window.location.href.substring(keyPos+(key+"=").length, ampPos === -1 ? window.location.href.length : ampPos);
}