index.js

/**
 * Module dependencies.
 */

var trim = require('trim');
var type = require('type');

var pattern = /(\w+)\[(\d+)\]/;

/**
 * Safely encode the given string
 * 
 * @param {String} str
 * @return {String}
 * @api private
 */

var encode = function(str) {
  try {
    return encodeURIComponent(str);
  } catch (e) {
    return str;
  }
};

/**
 * Safely decode the string
 * 
 * @param {String} str
 * @return {String}
 * @api private
 */

var decode = function(str) {
  try {
    return decodeURIComponent(str.replace(/\+/g, ' '));
  } catch (e) {
    return str;
  }
}

/**
 * Parse the given query `str`.
 *
 * @param {String} str
 * @return {Object}
 * @api public
 */

exports.parse = function(str){
  if ('string' != typeof str) return {};

  str = trim(str);
  if ('' == str) return {};
  if ('?' == str.charAt(0)) str = str.slice(1);

  var obj = {};
  var pairs = str.split('&');
  for (var i = 0; i < pairs.length; i++) {
    var parts = pairs[i].split('=');
    var key = decode(parts[0]);
    var m;

    if (m = pattern.exec(key)) {
      obj[m[1]] = obj[m[1]] || [];
      obj[m[1]][m[2]] = decode(parts[1]);
      continue;
    }

    obj[parts[0]] = null == parts[1]
      ? ''
      : decode(parts[1]);
  }

  return obj;
};

/**
 * Stringify the given `obj`.
 *
 * @param {Object} obj
 * @return {String}
 * @api public
 */

exports.stringify = function(obj){
  if (!obj) return '';
  var pairs = [];

  for (var key in obj) {
    var value = obj[key];

    if ('array' == type(value)) {
      for (var i = 0; i < value.length; ++i) {
        pairs.push(encode(key + '[' + i + ']') + '=' + encode(value[i]));
      }
      continue;
    }

    pairs.push(encode(key) + '=' + encode(obj[key]));
  }

  return pairs.join('&');
};