Just like the jQuery's one http://api.jquery.com/jQuery.isWindow/. But more relible.
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isWindow
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| function( | |
| a, // input | |
| b // placeholder for property document of a | |
| ){ | |
| return | |
| // cannot be falsy value, mainly to prevent null and undefined (regarded as global object in some browsers) | |
| !!a && | |
| // checking types with Object.prototype.toString.call is always a good way | |
| // however, for window, is a bit difficult | |
| // let's see the results in different browsers (except IE678, which return "[object Object]") | |
| // "[object Window]" | |
| // "[object DOMWindow]" | |
| // "[object global]" | |
| // so, we can simply check if the input's [[Class]] is ended with w] or l] | |
| /[wl]]/.test({}.toString.call(a)) || | |
| // believe me, IE is not a good guy | |
| // why? | |
| // because in which, window == document but document != window | |
| // what a wtf feature! | |
| a == (b=a.document) && b != a | |
| } |
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| (function(a,b){return!!a&&/[wl]]/.test({}.toString.call(a))||a==(b=a.document)&&b!=a}) |
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| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| Version 2, December 2004 | |
| Copyright (C) 2011 YOUR_NAME_HERE <YOUR_URL_HERE> | |
| Everyone is permitted to copy and distribute verbatim or modified | |
| copies of this license document, and changing it is allowed as long | |
| as the name is changed. | |
| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION | |
| 0. You just DO WHAT THE FUCK YOU WANT TO. |
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| { | |
| "name": "isWindow", | |
| "description": "Check if the input is window.", | |
| "keywords": [ | |
| "window", | |
| "isWindow", | |
| "DOM", | |
| "jQUery" | |
| ] | |
| } |
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| <!DOCTYPE html> | |
| <title>Foo</title> | |
| <div>Expected value: <b>true</b></div> | |
| <div>Actual value: <b id="ret"></b></div> | |
| <script> | |
| // write a small example that shows off the API for your example | |
| // and tests it in one fell swoop. | |
| var myFunction = (function(a,b){return!!a&&/[wl]]/.test({}.toString.call(a))||a==(b=a.document)&&b!=a}) | |
| document.getElementById( "ret" ).innerHTML = myFunction(window) | |
| </script> |
You can even eliminate the toString call completely, because .test() coerces its first argument into String.
You could try a&&a.alert additionally
@atk: Thanks again! But an fake object {alert:1,toString:function(){return 'w]'}} still passes the test.
That's true. How about (a||0).constructor===this.Window? Works in all modern browsers (not in IE 7 or older).
Not in Chrome 14.
this.constructor !== window
Damn, there it's DOMWindow... /Wi/.test(a.constructor), maybe?
{constructor:'Wi'}
Let's try this:
function(a,b){b=this.Window||this.DOMWindow;return!!a&&b?a instanceof b:a==(b=a.document)&&b!=a}
It is sad that it won't work with iframes...
Rewritten to probably work with (i)frames:
function(a,b){return!!a&&(b=a.Window||a.DOMWindow)?a instanceof b:a==(b=a.document)&&b!=a}
It cannot work with my chromium 12...
Alas, it's not exposed in Chrome. OK, let's try this:
function(a,b){return!!a&&(b=top.constructor)?a instanceof b:a==(b=a.document)&&b!=a}
It won't work with (i)frame as well, because the scope of top differs from (i)frame.
Right. Any idea how to get DOMWindow in Chrome if its not exposed?
The magic __proto__?
Doesn't help very much, because it is different between frames.
I think it is hard. In fact, the original code is enough.
Try this:
function(a,b){return a&&a==a[b='window']&&a==a[b][b]}
Clever. Exploiting the fact that any global object is exposed as a property of window, and window itself is a global object.
@phoetry: It's clever but it won't work.
var a = {};
a.window = a;
(function(a,b){return a&&a==a[b='window']&&a==a[b][b]})(a) // true
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I'd say it's safe to eliminate the Object {} scope from the toString() call.