list.item(0) vs list[0]

Question

document.getElementsByTagName('a').item(0)

and

document.getElementsByTagName('a')[0]

will return the same result...

Is the former faster than the latter, maybe someone knows of test results?

Answer 1

Selfmade performance test: http://jsfiddle.net/438jh/2/

The difference seems to be negligible. The second method performs better in most case, but if you have a look on how often the loop is performed it does not really matter.

Chrome:

1. method: ~260ms
2. method: ~170ms

Answer 2

item function is a member of NodeList DOM object. NodeLists are array-like but they are not real arrays (e.g.: they are live, read-only, lack of array functions).

The performance difference should be negligible.

Answer 3

For a more practical example, this technique has the best performance. Look at work by Nicholas Zakas, YAHOO! for more examples:

var cachedDOMquery = Array.prototype.slice.apply(document.getElementsByTagName('a')),
i = cachedDOMquery.length,
item;
while(i--){
    item = cachedDOMquery[i];
    alert(item.href);
}