function is_array (mixed_var) {
  // http://kevin.vanzonneveld.net
  // +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // +   improved by: Legaev Andrey
  // +   bugfixed by: Cord
  // +   bugfixed by: Manish
  // +   improved by: Onno Marsman
  // +   improved by: Brett Zamir (http://brett-zamir.me)
  // +   bugfixed by: Brett Zamir (http://brett-zamir.me)
  // +   improved by: Nathan Sepulveda
  // +   improved by: Brett Zamir (http://brett-zamir.me)
  // %        note 1: In php.js, javascript objects are like php associative arrays, thus JavaScript objects will also
  // %        note 1: return true in this function (except for objects which inherit properties, being thus used as objects),
  // %        note 1: unless you do ini_set('phpjs.objectsAsArrays', 0), in which case only genuine JavaScript arrays
  // %        note 1: will return true
  // *     example 1: is_array(['Kevin', 'van', 'Zonneveld']);
  // *     returns 1: true
  // *     example 2: is_array('Kevin van Zonneveld');
  // *     returns 2: false
  // *     example 3: is_array({0: 'Kevin', 1: 'van', 2: 'Zonneveld'});
  // *     returns 3: true
  // *     example 4: is_array(function tmp_a(){this.name = 'Kevin'});
  // *     returns 4: false
  var ini,
    _getFuncName = function (fn) {
      var name = (/\W*function\s+([\w\$]+)\s*\(/).exec(fn);
      if (!name) {
        return '(Anonymous)';
      }
      return name[1];
    },
    _isArray = function (mixed_var) {
      // return Object.prototype.toString.call(mixed_var) === '[object Array]';
      // The above works, but let's do the even more stringent approach: (since Object.prototype.toString could be overridden)
      // Null, Not an object, no length property so couldn't be an Array (or String)
      if (!mixed_var || typeof mixed_var !== 'object' || typeof mixed_var.length !== 'number') {
        return false;
      }
      var len = mixed_var.length;
      mixed_var[mixed_var.length] = 'bogus';
      // The only way I can think of to get around this (or where there would be trouble) would be to have an object defined
      // with a custom "length" getter which changed behavior on each call (or a setter to mess up the following below) or a custom
      // setter for numeric properties, but even that would need to listen for specific indexes; but there should be no false negatives
      // and such a false positive would need to rely on later JavaScript innovations like __defineSetter__
      if (len !== mixed_var.length) { // We know it's an array since length auto-changed with the addition of a
      // numeric property at its length end, so safely get rid of our bogus element
        mixed_var.length -= 1;
        return true;
      }
      // Get rid of the property we added onto a non-array object; only possible
      // side-effect is if the user adds back the property later, it will iterate
      // this property in the older order placement in IE (an order which should not
      // be depended on anyways)
      delete mixed_var[mixed_var.length];
      return false;
    };

  if (!mixed_var || typeof mixed_var !== 'object') {
    return false;
  }

  // BEGIN REDUNDANT
  this.php_js = this.php_js || {};
  this.php_js.ini = this.php_js.ini || {};
  // END REDUNDANT

  ini = this.php_js.ini['phpjs.objectsAsArrays'];

  return _isArray(mixed_var) ||
    // Allow returning true unless user has called
    // ini_set('phpjs.objectsAsArrays', 0) to disallow objects as arrays
    ((!ini || ( // if it's not set to 0 and it's not 'off', check for objects as arrays
    (parseInt(ini.local_value, 10) !== 0 && (!ini.local_value.toLowerCase || ini.local_value.toLowerCase() !== 'off')))
    ) && (
    Object.prototype.toString.call(mixed_var) === '[object Object]' && _getFuncName(mixed_var.constructor) === 'Object' // Most likely a literal and intended as assoc. array
    ));
}

is_array(['Kevin', 'van', 'Zonneveld']);

true

is_array('Kevin van Zonneveld');

false

is_array({0: 'Kevin', 1: 'van', 2: 'Zonneveld'});

true