1 Posted by Richard York on 30 January 2006 | Permalink

Why not use something like Dean Edwards's cssQuery()? Not only can you get multiple elements by tag name, but I find using css selectors in JS to be much more useful.

2 Posted by Robert Nyman on 30 January 2006 | Permalink

I see it as useful if you want to avoid classes on a lot of elements that you're looking for. Otherwise, my http://www.robertnyman.com/2005/11/07/the-ultimate-getelementsbyclassname/ or http://www.robertnyman.com/2006/01/23/monday-code-giveaway-getelementsbyattribute/ are as useful.

3 Posted by courtenay on 1 February 2006 | Permalink

This requires a few helpers from prototype.js; $A and 'each', which is just a simple iterator; and 'bind' (which uses apply). Sorry for the formatting, it's your comments.

Object.prototype.getElementsByTagNames = function() {
var ret = $A(new Array());
var tags = $A((arguments.length == 1 && arguments[0].constructor == Array) ? arguments[0] : arguments)
tags.each( function(tag,j) {
$A(this.getElementsByTagName(tag)).each (function(iter) { ret.push(iter); }
);
}.bind(this));
return ret;

works like
somenode.getElementsByTagNames('A','div');
somenode.getElementsByTagNames(['a','div']);

4 Posted by Theodor Zoulias on 2 February 2006 | Permalink

Nice! Sorting a big result array has some performance implications though. Opera's implementation for sourceIndex is very slow. A quick test reveals that a more trivial implementation of getElementsByTagNames may be preferable, if the expected result array contains more than 10% of all document elements.

http://users.freestuff.gr/skeftomilos/demos/get-elements-by-tag-names/get-elements-by-tag-names-test.htm

5 Posted by Howard on 8 February 2006 | Permalink

Building collections can be expensive; if your list of tags is longish,
it's likely to be more efficient to simply get *all* elements and then
just select the ones you want from it. Doing it that way also removes
the need to sort: they'll already be in order.

(No error checking; untested):

function getElementsByTagNames(list,obj) {
var tags = {}, i, result = [], elms;
obj = obj || document;
var tags = {};
for (var i=0; i<list.length; i++)
tags[list[i].toUpperCase()] = true;
elms = obj.getElementsByTagName('*');
for (i=0; i<elms.length; i++)
if (elms[i].tagName in tags) result.push(elms[i]);
return result;
}

then ...

var element = document.getElementById('test');
var formFieldList = getElementsByTagNames(['input','select','textarea'],element);