qurl.js

var Qurl;

(function() {
  'use strict';

  var proto;

  Qurl = function() {
    if (!(this instanceof Qurl)) {
      return new Qurl();
    }
  }

  proto = Qurl.prototype;

  proto.query = function(key, value) {
    if (!key) {
      return getSearch();
    }

    if (key && typeof(value) === 'undefined') {
      return getSearch()[key];
    }

    if (key && typeof(value) !== 'undefined') {
      return setSearch(key, value);
    }
  };

  function getSearch() {
    var string = window.location.search,
      pairs = [],
      obj = {};

    if (!string) {
      return obj;
    }
    string = string.replace('?', '');

    pairs = string.split('&');
    pairs.forEach(function(p) {
      var pair = decodeURIComponent(p).split('='),
        key = pair[0],
        val = pair[1];

      obj[key] = val;
    });

    return obj;
  }

  function setSearch(key, value) {
    var search = getSearch(),
      string = window.location.search;

    if (value === false) {
      delete search[key];
    } else {
      search[key] = value;
    }

    setSearchString(getSearchString(search));

    return search;
  }

  function setSearchString(string) {
    if (history.pushState) {
      history.pushState({}, document.title, string);
    }
  }

  function getSearchString(query) {
    var pairs = [];

    Object.keys(query).forEach(function(key) {
      if (typeof query[key] === 'undefined') {
        pairs.push(key);
      } else {
        pairs.push(encodeURIComponent(key) + '=' + encodeURIComponent(query[key] || ''));
      }
    });

    if (pairs.length === 0) {
      return '?';
    } else {
      return '?' + pairs.join('&');
    }
  }

  Qurl.create = Qurl;
}());