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Created June 24, 2011 10:20
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Array.prototype.unique
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README.md

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.

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annotated.js
function(){
// make sure
// to annotate
// your code
// so everyone
// can learn
// from it!
// see jed's entries
// for examples.
}
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index.js
function(){/* Your entry, a useful, unique, and valid JavaScript expression that packs as much functionality into 140 bytes as possible. */}
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LICENSE.txt
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.
Raw
package.json
{
"name": "theNameOfYourLibWhichMustBeAValidCamelCasedJavaScriptIdentifier",
"description": "This should be a short description of your entry.",
"keywords": [
"five",
"descriptive",
"keywords",
"or",
"fewer"
]
}
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test.html
<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>
@atk
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atk commented Jun 26, 2011

What about using ~ instead of <0?

@jed
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jed commented Jun 26, 2011

try it and you'll see why. ;)

@atk
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atk commented Jun 26, 2011

Got it. Well, then how about

Array.prototype.unique=[].unique||function(a,b){for(a=this,b=a.length;b--;a.indexOf(a[b])<b&&a.splice(b,1));return a}

does not forcefully overwrite the original method and is still 3 bytes shorter.

@jed
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jed commented Jun 27, 2011

it may be shorter, but it's also destructive. probably not a good idea for something like unique.

@atk
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atk commented Jun 27, 2011

A bit longer (133 chars), but not destructive:

Array.prototype.unique||(Array.prototype.unique=function(a,b){for(a=this,b=a.length;b--;a.indexOf(a[b])<b&&a.splice(b,1));return a})

Or if you want to use your filter version (even shorter), take one of the anonymous functions out of the closure:

Array.prototype.unique||(Array.prototype.unique=function(){return this.filter(function(a,b,c){return c.indexOf(a,b+1)<0})})

@jed
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jed commented Jun 27, 2011

this isn't an ES5 shim, so i'm not sure we need to worry about overwriting anything. by destructive i mean that your version mutates the original array.

@atk
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atk commented Jun 27, 2011

Ah, well, then at least the removal of the closure should bring some less bytes.

@jed
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jed commented Jun 27, 2011

well, given it's a bit of an expensive operation, i'd prefer the caching of the function. @WebReflection has a really good sense for that stuff.

@sichain
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sichain commented Nov 23, 2012

hi. awesome function, thanks on that!

on a = [ 1,2,3,4,3,2,1] your version returns
[4, 3, 2, 1]
which might be disappointing if we want to have the first occurrence to be first in result set

so if you do it like that
Array.prototype.unique=function(a){return function(){return this.filter(a)}}(function(a,b,c){return c.indexOf(a)==b})
it'll return
[1, 2, 3, 4]

of course it might affect performance

thanks again!

@neolectron
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[1,2,3,1].reduce((acc, item) => acc.includes(item) ? acc : acc.concat(item), [])
is simpler

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ghost commented Oct 27, 2017 •
edited by ghost
Loading 

Array.prototype.uniq =
Array.prototype.unique = 
  ( () => function()
    { return [ ...new Set( this ) ] } 
  ) ()

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