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Created June 17, 2011 15:37
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140byt.es polyfill for Array.filter
Raw
README.md

140byt.es polyfill for Array.filter

Thanks to atk and jdalton for making the solution more robust and compliant! :)

Raw
annotated.js
[].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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index.js
[].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})
Raw
LICENSE.txt
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.
Raw
package.json
{
"name": "arrayFilter140Polyfill",
"description": "A tweet-sized polyfill for Array.prototype.filter",
"keywords": [
"array",
"filter",
"polyfill",
"prototype"
]
}
Raw
test.html
<!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>
@maettig
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maettig commented Nov 24, 2011

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.

@jdalton
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jdalton commented Nov 24, 2011

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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