Parse that Querystring with VanillaJS

Because sometimes you need that data!


Parsing your querystrings with plain-old javascript has never been easier! For the developer that wants to code every line, or perhaps needs every drop of power/speed their browser can muster, VanillaJS is the winner. So here is a VanillaJS version of my querystring parser that does not require jQuery to run.

What is VanillaJS

VanillaJS is a loving name given to plain-old javascript, that’s right, the same javascript that you know and love is VanillaJS!


 *  querystring.js - v1.0.0
 *  Querystring utility in Javascript
 *  Made by Eldon McGuinness
 *  Under MIT License
 *  Parameters:
 *  str - A string that you want the script to treat as the querystring
 *        instead of the actual page's querystring.

queryString = function(str) {
    var qso = {};
    var qs = (str ||;

    // Check for an empty querystring
    if (qs == ""){
        return qso;
    // Normalize the querystring
    qs = qs.replace(/(^\?)/,'')
    while (qs.indexOf("&&") != -1){
        qs = qs.replace(/&&/g,'&');
    qs = qs.replace(/([\&]+$)/,'');

    // Break the querystring into parts

    qs = qs.split("&");

    // Build the querystring object
    for (var i=0; i < qs.length; i++){
        var qi = qs[i].split("=");

        qi = map(qi, function (n) {return decodeURIComponent(n)});

        if (qso[qi[0]] != undefined){

            // If a key already exists then make this an object
            if (typeof(qso[qi[0]]) == "string"){
                var temp = qso[qi[0]];
                if (qi[1] == ""){
                    qi[1] = null;
                //console.log("Duplicate key: ["+qi[0]+"]["+qi[1]+"]");
                qso[qi[0]] = [];

            }else if (typeof(qso[qi[0]]) == "object"){
                if (qi[1] == ""){
                    qi[1] = null;
                //console.log("Duplicate key: ["+qi[0]+"]["+qi[1]+"]");
            // If no key exists just set it as a string
            if (qi[1] == ""){
                qi[1] = null;
            //console.log("New key: ["+qi[0]+"]["+qi[1]+"]");
            qso[qi[0]] = qi[1];

    function map(arr, func){
        for (var i=0; i<arr.length; i++ ){
            arr[i] = func(arr[i]);
        return arr;
    return qso;


To get the results of the querystring you simply need to invoke the plugin. additionally, you can refer directly to the part of the object that you want.

//To copy the entire querystring object into a variable 
var queryString = querystring();

//To get only the field named "q"
var query = querystring()["q"];

//Remember, if there is more than one item with the same name, you will get an
//array that contains the responses.
//Example URL: /page.html?q=something&q=somethingelse
var query = querystring()["q"];

//query[0] yields the string "something"
//query[1] yields the string "somethingelse"

Useful Right!?

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Corrections or Changes

If you think something is not right or should be changed, feel free to comment or submit fixes on Github.

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