Status of Array extras in ECMA 4

David Golightly davigoli at
Sat Sep 1 10:07:12 PDT 2007

I'm curious as to the fate of the famous JavaScript 1.6 Array extras
(indexOf, lastIndexOf, forEach, map, filter, every, some) in ECMAScript 4.
As a JavaScript developer, I've come to greatly appreciate the
functional-style flexibility these methods offer, and have incorporated
implementations of them into my everyday JS toolkit.  (See: and if
you're not familiar with the Array extras.)

However, according to the current ECMAScript 4 specification, these methods
appear to be missing from Array.prototype:

Given the significant performance boost from moving this sort of iteration
into machine code from interpreted code, I for one would greatly appreciate
an official endorsement of these methods in ECMAScript 4.  They certainly
seem to fit within the spirit of the existing ECMAScript 3 native array
methods (slice, splice, etc.) and have parallels in the String prototype
(indexOf, lastIndexOf).  Is there a reason not to include them in ECMA 4?
If so, what might that be?


David Golightly
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