JavaScript Performance: Fast DOM Iterator

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JavaScript Performance: Fast DOM Iterator

After numerous tests, this function provides the most performant way to iterate over all the elements in the DOM:

function walkTheDom() {

var items = document.getElementsByTagName("*");

var i=items.length;

var item;

{

item = items[i];

//Do something with item

}

while (--i);

}

Print posted @ Thursday, March 02, 2006 4:13 AM

Feedback

# re: JavaScript Performance: Fast DOM Iterator

Interesting... can you elaborate on the different methods you tested and the times they took? 3/3/2006 7:51 AM | Patrick Fitzgerald

# re: JavaScript Performance: Fast DOM Iterator

Hey Patrick ... you can check out my test page here

http://michaelparsons.ca/javascriptperformance.htm
3/3/2006 8:32 AM | Mike Parsons

# re: JavaScript Performance: Fast DOM Iterator

hi mike. i was intersted about you project. (MyAJAXToolKit). is there any news/progress about it? 8/14/2006 4:47 AM | mike

# re: JavaScript Performance: Fast DOM Iterator

You got a bug in the code - the first item is out of range. It should read item = items[i-1];

Otherwise: Thanks! 3/9/2008 9:15 AM | Johannes

# re: JavaScript Performance: Fast DOM Iterator

i--;
do {
item = items[i];
//Do something with item
}
while(i--);

also the expression in *while* must
be post-decrement instead,
otherwise you'll miss item[0].

cheers
2/26/2009 2:51 AM | Anonymous

# re: JavaScript Performance: Fast DOM Iterator

i just understood how it works when applying the suggestion of Johannes. in his fix it must stay pre-increment:

do {
item = items[i-1];
//Do something with item

}
while(--i);
2/26/2009 2:57 AM | Anonymous

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