Comments on: Array Extras

By: Patrick Kwinten

Patrick Kwinten — Wed, 26 Mar 2008 14:41:57 +0000

thanks for the help, I had some problem with using prototype and defining arrays, some how using

var tagMap= new Array()

causes that prototype adds other elements to the array

By: JavaScript Scripting Essentials

JavaScript Scripting Essentials — Thu, 01 Mar 2007 11:16:55 +0000

[...] Dan Webb asks what are your JavaScript essentials? Those bits and pieces you can’t live without that get copy/pasted from project to project. His pragmatic list includes the $ function, getElementsByClassName, Dean’s event handling, the JS 1.6 array methods, and the DOMContentLoaded event. His full script that he guarantees he _won’t_ support is here. [...]

By: Scripting Essentials » Professional Web Software Development

Scripting Essentials » Professional Web Software Development — Tue, 23 Jan 2007 21:01:02 +0000

[...] Javascript’s new forEach() function. Thanks to Dean Edwards, there is a cross browser solution, that is extremely simple to use. There are some other new functions as well that I haven’t explored yet, but they are worth noting. [...]

By: Ajaxian » JavaScript Scripting Essentials

Ajaxian » JavaScript Scripting Essentials — Sun, 14 Jan 2007 22:48:23 +0000

By: Erik Arvidsson

Erik Arvidsson — Tue, 26 Dec 2006 21:55:58 +0000

Jan: That is just a typo. You should remove that.

By: Jan van Casteren

Jan van Casteren — Mon, 18 Dec 2006 15:58:13 +0000

Thank you for this handy script. One question: is there any reason to have the obj parameter in the copy method?

See:

Array.prototype.copy = function (obj) {
return this.concat();
};

By: Jeff Walden

Jeff Walden — Sun, 17 Dec 2006 15:17:57 +0000

Actually, let me backtrack for a second — I’m not sure the docs I was referencing were canonical. I’ll get back with more details later…

By: Jeff Walden

Jeff Walden — Sun, 17 Dec 2006 15:12:33 +0000

Your code for Array.prototype.lastIndexOf has a bug in it: when the second argument is a negative number and the sum of that argument and the array’s length is less than zero, you might erroneously return 0 when searching for the first element in the array. For example:

[2].lastIndexOf(2, -5)

…will return 0 with your code, when according to the function’s description it should return -1. The fix should be to replace |Math.max(0, this.length + fromIndex)| with |this.length + fromIndex| in the lastIndexOf implementation.

Also, don’t bother testing behavior in Firefox, because Firefox has this bug (and an indexOf bug which is a little harder to duplicate). I’m checking whether non-Firefox implementations demonstrate this and the other bug to evaluate how feasible it is to fix this behavior in point releases to stable Firefox versions. (The bug is https://bugzilla.mozilla.org/show_bug.cgi?id=364104 if you’re interested.)

By: Johan Sundström

Johan Sundström — Sun, 05 Nov 2006 11:30:11 +0000

More of a reflection than suggestion: testing for Array.prototype.forEach and friends this way rather than by way of Array.prototype.hasOwnProperty(’forEach’) will find Object.prototype.forEach when no Array specific implementation exists. This is probably still often what you want, assuming that the Object prototype internally handles different data types differently in sane manners, but once in a while it might not be.

By: Thomas Frank

Thomas Frank — Fri, 14 Jul 2006 12:00:15 +0000

Brilliant! Thanks!