Prevent from type converting of "this" during a call to a function with apply

Servus Ninjas,

this is what ecmascript 5 spec. (page 118) in the section Function.prototype.apply(thisArg, argArray) says:

NOTE: The thisArg value is passed without modification as the this value. This is a change from Edition 3, where a undefined or null thisArg is replaced with the global object and ToObject is applied to all other values and that result is passed as the this value.

This sounds promising, but this spec isn't implemented yet in any of the modern browsers so we开发者_开发问答 have to deal with the 3rd spec implementation.

My question now is „How to get the typeof statement become TRUE?“

var foo = function (arg1, arg2) {
      alert(typeof this == "string");
};

foo.apply("bar", ["arg1", "arg2"]);

any ideas?

There's 2 types of strings in JavaScript.

The ones with typeof string

"hello"

and the ones with typeof object

new String("hello");

apply will always wrap any value you pass as an object since you need to use it through the this keyword.

Either use this instanceof String (same window-only) or use Object.prototype.toString.call(this) === "[object String]" (works across windows).

The one and only thing at the moment is to check the type

with Object.prototype.toString.call(string) == "[object String]"; and convert this back to String like:

    var isString = function(string) {
      return Object.prototype.toString.call(string) == "[object String]";
    };

    var isNumber = function(number) {
      return Object.prototype.toString.call(number) == "[object Number]";
    };

    var toRightType = function(mess) {
      if(isString(mess)) {
        mess = mess+"";
      }

      if(isNumber(mess)) {
        mess = mess+0;
      }

      return mess;
    };


    var foo = function () {
      var _this = toRightType(this);
    };

    foo.apply("bar");

This is on of the sad chapters in javascript :(