null / undefined将替换为IE9以外的所有浏览器中的全局对象

Question

When I do this:

Object.prototype.toString.call( null )

or this:

Object.prototype.toString.call( )

the browsers return the following string value (in both cases):

Chrome 9: [object global]
Safari 5: [object DOMWindow]
Firefox 3.6: [object Window]
Opera 11: [object Window]

However in IE9 RC the return values are [object Null] and [object Undefined] respectively.

The ES5 specification states:

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.

See here: http://es5.github.com/#x15.3.4.4

Does this mean that IE9 is the only browser that follows this newly introduced rule?

Answer 1

I'm going to go out on a limb and say yes . ;)

FYI, I just tested FF4, and it gives [object Null] and [object Undefined]