IE的typeof window.close有所不同

Question

Today I saw weird behavior when I typed window.close it showing function close() { [native code] } in IE and function () { [native code] } in chrome, I thought both are function.

But when I typed typeof(window.close) it showing 'object' in IE8 and 'function' in chrome.

Why this different behavior? What are the ways I can use to check type of a variable in JavaScript? Is there other functions which shows this type of behavior?

Thanks

Answer 1

Look here for what you should have (ie "function" ).

And here for the less readable but official ECMAScript reference.

IE 8 simply doesn't follow the norm. That's really not the sole occurrence.

Regarding the How to test if a variable is a function on IE8 ? question, I can't test it myself but this probably works :

var myvar = window.close;
var isfunc = Object.prototype.toString.call( myvar ) === '[object Function]';