A 140 bytes Array.prototype.reduce solution.
It should work as described on MDN.
If the array has no value and no initial value is passed, it raises an error. If the callback is not a function, it will fail when tempting to call it.
There is one major difference between ES5 specifications and this implementation: if the second parametter is specified but undefined, it won't be taken as initial value. There is no place to put a arguments.length here :(
| Array.prototype.reduce = | |
| [].reduce || // if not defined yet | |
| function( | |
| c, // callback function | |
| v // initial value (optionnal) | |
| ) { | |
| for( // iterate | |
| // make actions in the first for statement, save one ';' :) | |
| var t=this | |
| , u // undefined | |
| , i= // initialize i to: | |
| (u=v===u) // if initial value is not defined | |
| ? (v=t[0],1) // set initial value to first value and set i to 1 | |
| : 0; // else set i to 0 | |
| // for loop condition | |
| i < t.length; | |
| ) | |
| // for loop body | |
| v=c(v,t[i],i++,t); // call the callback with the arguments, save the result value | |
| i<2 & u && // if the array was empty and no default value was given | |
| u(); // raise a TypeError (u is not a function) | |
| return v // else return the result | |
| } |
| Array.prototype.reduce=[].reduce||function(c,v){for(var t=this,u,i=(u=v===u)?(v=t[0],1):0;i<t.length;)v=c(v,t[i],i++,t);i<2&u&&u();return v} |
| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| Version 2, December 2004 | |
| Copyright (C) 2011 Benoît Zugmeyer <alk at graou dot fr> | |
| 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": "ArrayReduce140", | |
| "description": "An Array:reduce method implementation in 140 bytes.", | |
| "keywords": [ | |
| "array", | |
| "reduce" | |
| ] | |
| } |
| <!DOCTYPE html> | |
| <title>Foo</title> | |
| <div>Expected value: <b>15</b></div> | |
| <div>Actual value: <b id="ret"></b></div> | |
| <script> | |
| Array.prototype.reduce=[].reduce||function(c,v){for(var t=this,u,i=(u=v===u)?(v=t[0],1):0;i<t.length;)v=c(v,t[i],i++,t);i<2&u&&u();return v} | |
| document.getElementById( "ret" ).innerHTML = [1,2,3,4,5].reduce(function(a, b) { return a + b; }); | |
| </script> |
awesome. you're probably the best man to tackle reduceRight too, so please give it a shot!
This fallback is not ES5 compliant.
Also browsers like Chrome have a bug where Array.prototype.reduce = [].reduce will cause Array#reduce to become enumerable.
For more information on what can be changed to make this method ES5 complaint and info on a critical bug, that this gist shares, please see my comments on a similar gist.
I wonder why initial value in Chrome can't be an empty array!
I'll write an example later. I changed the æ trick to u(), which is on byte more (æ is two bytes) but raises a TypeError (which is expected).