Is one way more efficient? Are there any limitations in one method versus the other? Thanks for any input you guys can give me ;-)
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2 Answers
The Array.prototype.forEach method is part of the ECMAScript 5th Edition Specification, is available on all browsers but not in IE.
I would suggest you to use a simple sequential for loop, IMO is more efficient since forEach needs a callback function, a function will be created starting a closure and you don't need to care about IE.
But if you want to use forEach and all the other new Array.prototype methods such as map, filter, every, some, etc... you can add an implementation for IE, in the pages I linked.
answered Jun 14, 2010 at 23:32
Christian C. Salvadó
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2 Comments
unomi
just a note: forEach is more efficient on, so far, Opera and Chrome.
Christian C. Salvadó
I find
forEach lightning fast on Firefox, I've made a simple performance test, feel free to play with it.Similar to for each but supported in all browsers
for (var i = 0, myArrayElement; myArrayElement = myArray[i]; i++) { //now you can just use // myArrayElement // instead of // myArray[i] } Just to be aware, I use this when iterating though form collections (ie document.forms[0].elements)
4 Comments
Christian C. Salvadó
Just take note that the loop will be braked prematurely if an array element value is falsy (
0, null, undefined, NaN, an empty string, and of course false). Try with var myArray = [0, 1, 2];
John Hartsock
Good Point CMS. Just to be aware I use this when iterating though form collections (ie document.forms[0].elements)
Warty
you should stick the comment you just made in your main reply. Then we can +1 you.
cryo
for (var x,i=0; x=data[i++];) {...} is another way of doing this, but it still has the 'falsy' problem. See also stackoverflow.com/questions/2971698/…, see #7 for an example of how to do it without requiring items evaluating to true, although it's quite messy :-)