Thanks to atk and jdalton for making the solution more robust and compliant! :)
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140byt.es polyfill for Array.filter
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| [].filter || (Array.prototype.filter = // Use the native array filter method, if available. | |
| function(a, //a function to test each value of the array against. Truthy values will be put into the new array and falsy values will be excluded from the new array | |
| b, // placeholder | |
| c, // placeholder | |
| d, // placeholder | |
| e // placeholder | |
| ) { | |
| c = this; // cache the array | |
| d = []; // array to hold the new values which match the expression | |
| for (e in c) // for each value in the array, | |
| ~~e + '' == e && e >= 0 && // coerce the array position and if valid, | |
| a.call(b, c[e], +e, c) && // pass the current value into the expression and if truthy, | |
| d.push(c[e]); // add it to the new array | |
| return d // give back the new array | |
| }) |
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| [].filter||(Array.prototype.filter=function(a,b,c,d,e){c=this;d=[];for(e in c)~~e+''==e&&e>=0&&a.call(b,c[e],+e,c)&&d.push(c[e]);return d}) |
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| DO WHAT THE **** YOU WANT TO PUBLIC LICENSE | |
| Version 2, December 2004 | |
| Copyright (C) 2011 Eli Perelman http://eliperelman.com | |
| 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 **** YOU WANT TO PUBLIC LICENSE | |
| TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION | |
| 0. You just DO WHAT THE **** YOU WANT TO. |
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| { | |
| "name": "arrayFilter140Polyfill", | |
| "description": "A tweet-sized polyfill for Array.prototype.filter", | |
| "keywords": [ | |
| "array", | |
| "filter", | |
| "polyfill", | |
| "prototype" | |
| ] | |
| } |
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| <!DOCTYPE html> | |
| <title>Array filter polyfill</title> | |
| <div>Expected value: filter the array values outside of our range (less than 6)</div> | |
| <script> | |
| [].filter||(Array.prototype.filter=function(a,b,c,d,e){c=this;d=[];for(e in c)~~e+''==e&&e>=0&&a.call(b,c[e],+e,c)&&d.push(c[e]);return d}); | |
| var arr = [1,2,3,4,5,6,7,8,9,10]; | |
| // creates new array of [1,2,3,4,5] and reassigns it to arr. | |
| arr = arr.filter(function(value) { | |
| return value < 6; | |
| }); | |
| </script> |
@ jdalton Are you saying this wouldn't work:
Array.prototype.filter = [].filter || (function()...
Chrome has a bug where Array.prototype.filter = [].filter will cause Array#filter to become enumerable.
Also there's still a typo in the test.html snippet.
This
Array.prototype.filter=[].filter||(Array.prototype.filter=should be this
[].filter||(Array.prototype.filter=...)
Ah, I see. We don't even want to execute the polyfill if the method exists. No reassignment.
Save 2 bytes.
[].filter||(Array.prototype.filter=function(a,b,c,d,e){d=[];for(e in c=this)~~e+''==e&&e>=0&&a.call(b,c[e],+e,c)&&d.push(c[e]);return d})
Is there a reason why you do ~~e+''==e and e>=0? From what I know both do (almost) the same, checking if e is a number (to be more precise, the first checks for an int, the second for a double). I think it's shorter to use a plain for loop. The following version is 133 bytes and works in IE7 and IE8.
[].filter||(Array.prototype.filter=function(a,b,c,d,e){c=this;d=[];for(e=0;e<c.length;e++)a.call(b,c[e],e,c)&&d.push(c[e]);return d})This also fixes a problem we came across in our getElementsByClassName. In IE7 and IE8 the for-in loop does not return numeric indices for elements with an ID. It returns the IDs instead for these elements. If you do (for example) document.getElementsByTagName('*') on a document where all elements contain an ID, all these elements will be skipped. Forcing e to be a number solves this problem.
@maettig the ~~e+''==e and e>=0 is to ensure the key is a number and it's not negative.
Your version skips the in check for sparse arrays. You really shouldn't be using these snippets in production code.
e>=0 is enough to check for non-negative numbers. Is it really necessary to check for decimal places? I forgot about sparse arrays. But as said, using for-in is broken in IE on NodeList's.
e>=0 is enough to check for non-negative numbers. Is it really necessary to check for decimal places?
the ~~e+''==e also guards against keys like 08 too.
I forgot about sparse arrays. But as said, using for-in is broken in IE on NodeList's.
There is only so many characters allowed. As I have said before code-golf is not appropriate for production code so please don't look for it to be a robust and to-the-letter solution. As it is, the currently solution meets mark for a workable approximation of Array#filter. The important part is we have at least brought up/made aware the issues with each variation.
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@jdalton Are you saying this wouldn't work:
Array.prototype.filter = [].filter || (function()...