JSFiddle - React, Tailwind, and code Playground

HTML

<h1>Parse Query String</h1>
<code id="result"></code>

JavaScript

function parseQueryString(query) {
        var obj = {},
            qPos = query.indexOf("?"),
		    tokens = query.substr(qPos + 1).split('&')
		    i = tokens.length - 1;
		if (qPos !== -1 || query.indexOf("=") !== -1) {
			for (; i >= 0; i--) {
				var s = tokens[i].split('=');
				obj[unescape(s[0])] = s.hasOwnProperty(1) ? unescape(s[1]) : null;
			};
		}
		return obj;
}


/* Demo */

// var queryString = window.location.search;
var queryString = 'window.location.href';

var obj = parseQueryString(queryString);
document.getElementById('result').innerHTML = JSON.stringify(obj);