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@tsaniel
Forked from 140bytes/LICENSE.txt
Created October 5, 2011 10:05
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isWindow

140byt.es

A tweet-sized, fork-to-play, community-curated collection of JavaScript.

How to play

  1. Click the Fork button above to fork this gist.
  2. Modify all the files to according to the rules below.
  3. Save your entry and tweet it up!

Keep in mind that thanks to the awesome sensibilities of the GitHub team, gists are just repos. So feel free to clone yours and work locally for a more comfortable environment, and to allow commit messages.

Rules

All entries must exist in an index.js file, whose contents are

  1. an assignable, valid Javascript expression that
  2. contains no more than 140 bytes, and
  3. does not leak to the global scope.

All entries must also be licensed under the WTFPL or equally permissive license.

For more information

The 140byt.es site hasn't launched yet, but for now follow @140bytes on Twitter.

To learn about byte-saving hacks for your own code, or to contribute what you've learned, head to the wiki.

140byt.es is brought to you by Jed Schmidt. It was inspired by work from Thomas Fuchs and Dustin Diaz.

function(){
// make sure
// to annotate
// your code
// so everyone
// can learn
// from it!
// see jed's entries
// for examples.
}
function(){/* Your entry, a useful, unique, and valid JavaScript expression that packs as much functionality into 140 bytes as possible. */}
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.
{
"name": "theNameOfYourLibWhichMustBeAValidCamelCasedJavaScriptIdentifier",
"description": "This should be a short description of your entry.",
"keywords": [
"five",
"descriptive",
"keywords",
"or",
"fewer"
]
}
<body>
<div>Expected value: <b>undefined</b></div>
<div>Actual value: <b id="ret"></b></div>
</body>
<script>
// write a small example that shows off the API for your example
// and tests it in one fell swoop.
var myFunction = function(){ /* the code here should be identical to the entry. */ }
var ret = myFunction()
document.getElementById( "ret" ) = ret
</script>
@nikola
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nikola commented Oct 5, 2011

I'd say it's safe to eliminate the Object {} scope from the toString() call.

@atk
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atk commented Oct 6, 2011

You can even eliminate the toString call completely, because .test() coerces its first argument into String.

@tsaniel
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tsaniel commented Oct 7, 2011

Thanks for your ideas, @nikola and @atk!
However,
@nikola: This may lead to error in older IE versions.
@atk: Something like 'w]' will pass the test.

@atk
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atk commented Oct 7, 2011

You could try a&&a.alert additionally

@tsaniel
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tsaniel commented Oct 7, 2011

@atk: Thanks again! But an fake object {alert:1,toString:function(){return 'w]'}} still passes the test.

@atk
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atk commented Oct 7, 2011

That's true. How about (a||0).constructor===this.Window? Works in all modern browsers (not in IE 7 or older).

@nikola
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nikola commented Oct 7, 2011

Not in Chrome 14.

this.constructor !== window

@atk
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atk commented Oct 7, 2011

Damn, there it's DOMWindow... /Wi/.test(a.constructor), maybe?

@tsaniel
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tsaniel commented Oct 7, 2011

{constructor:'Wi'}

@atk
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atk commented Oct 9, 2011

Let's try this:

function(a,b){b=this.Window||this.DOMWindow;return!!a&&b?a instanceof b:a==(b=a.document)&&b!=a}

@tsaniel
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tsaniel commented Oct 10, 2011

It is sad that it won't work with iframes...

@atk
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atk commented Oct 10, 2011

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}

@tsaniel
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tsaniel commented Oct 10, 2011

It cannot work with my chromium 12...

@atk
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atk commented Oct 10, 2011

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}

@tsaniel
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tsaniel commented Oct 11, 2011

It won't work with (i)frame as well, because the scope of top differs from (i)frame.

@atk
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atk commented Oct 11, 2011

Right. Any idea how to get DOMWindow in Chrome if its not exposed?

@tsaniel
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tsaniel commented Oct 11, 2011

The magic __proto__?

@atk
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atk commented Oct 11, 2011

Doesn't help very much, because it is different between frames.

@tsaniel
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tsaniel commented Oct 11, 2011

I think it is hard. In fact, the original code is enough.

@phoetry
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phoetry commented Dec 2, 2011

Try this:

function(a,b){return a&&a==a[b='window']&&a==a[b][b]}

@nikola
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nikola commented Dec 2, 2011

Clever. Exploiting the fact that any global object is exposed as a property of window, and window itself is a global object.

@tsaniel
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tsaniel commented Dec 3, 2011

@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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