jquery.ba-deparam.js

// jQuery Deparam - v0.1.0 - 6/14/2011
// http://benalman.com/
// Copyright (c) 2011 Ben Alman; Licensed MIT, GPL

(function(window) {
  // Creating an internal undef value is safer than using undefined, in case it
  // was ever overwritten.
  var undef;
  // A handy reference.
  var decode = decodeURIComponent;

  // Document $.deparam.
  window.deparam = function(text, reviver) {
    // The object to be returned.
    var result = {};
    // Iterate over all key=value pairs.
    text.replace(/\+/g, ' ').split('&').forEach(function(pair, index) {
      // The key=value pair.
      var kv = pair.split('=');
      // The key, URI-decoded.
      var key = decode(kv[0]);
      // Abort if there's no key.
      if ( !key ) { return; }
      // The value, URI-decoded. If value is missing, use empty string.
      var value = decode(kv[1] || '');
      // If key is more complex than 'foo', like 'a[]' or 'a[b][c]', split it
      // into its component parts.
      var keys = key.split('][');
      var last = keys.length - 1;
      // Used when key is complex.
      var i = 0;
      var current = result;

      // If the first keys part contains [ and the last ends with ], then []
      // are correctly balanced.
      if ( keys[0].indexOf('[') >= 0 && /\]$/.test(keys[last]) ) {
        // Remove the trailing ] from the last keys part.
        keys[last] = keys[last].replace(/\]$/, '');
        // Split first keys part into two parts on the [ and add them back onto
        // the beginning of the keys array.
        keys = keys.shift().split('[').concat(keys);
        // Since a key part was added, increment last.
        last++;
      } else {
        // Basic 'foo' style key.
        last = 0;
      }

      if ( typeof reviver === 'function' ) {
        // If a reviver function was passed, use that function.
        value = reviver(key, value);
      } else if ( reviver ) {
        // If true was passed, use the built-in $.deparam.reviver function.
        value = deparam.reviver(key, value);
      }

      if ( last ) {
        // Complex key, like 'a[]' or 'a[b][c]'. At this point, the keys array
        // might look like ['a', ''] (array) or ['a', 'b', 'c'] (object).
        for ( ; i <= last; i++ ) {
          // If the current key part was specified, use that value as the array
          // index or object key. If omitted, assume an array and use the
          // array's length (effectively an array push).
          key = keys[i] !== '' ? keys[i] : current.length;
          if ( i < last ) {
            // If not the last key part, update the reference to the current
            // object/array, creating it if it doesn't already exist AND there's
            // a next key. If the next key is non-numeric and not empty string,
            // create an object, otherwise create an array.
            current = current[key] = current[key] || (isNaN(keys[i + 1]) ? {} : []);
          } else {
            // If the last key part, set the value.
            current[key] = value;
          }
        }
      } else {
        // Simple key.
        if ( Array.isArray(result[key]) ) {
          // If the key already exists, and is an array, push the new value onto
          // the array.
          result[key].push(value);
        } else if ( key in result ) {
          // If the key already exists, and is NOT an array, turn it into an
          // array, pushing the new value onto it.
          result[key] = [result[key], value];
        } else {
          // Otherwise, just set the value.
          result[key] = value;
        }
      }
    });

    return result;
  };

  // Default reviver function, used when true is passed as the second argument
  // to $.deparam. Don't like it? Pass your own!
  deparam.reviver = function(key, value) {
    var specials = {
      'true': true,
      'false': false,
      'null': null,
      'undefined': undef
    };

    return (+value + '') === value ? +value // Number
      : value in specials ? specials[value] // true, false, null, undefined
      : value; // String
  };

}(this));