Extract the query parameters from a URL using Map/Reduce in JavaScript

gistfile1.js

/**
 * Extracts the query parameters from a URL
 * @url {string}  url to be analyzed
 * @return {string} params object with a property for each named URL query parameter set to the
 * value of the parameter.
 */ 
function getUrlParams(url) {
    // Note that a regex should be used to properly split the URL. I.e. an '=' inside a value will be lost
    // This function is just to demonstrate the usage of Map/Reduce
    var map = url.slice(url.indexOf('?') + 1).split('&').map(function(param) { return param.split('='); });
    map.unshift({});    // Insert empty object in the beginning of the array as the start for the reduce operation
    return map.reduce(function(params, arg, i){ params[arg[0]] = arg[1]; return params;});
}