Javascript - getElementID from scratch using BFS? - breadth-first-search

Question

I'm trying to learn javascript, and spent tonight writing a getElementByID() function using Breadth-First Search. In short: I'm lost.
Fiddle: http://jsfiddle.net/timdown/a2Fm6/
Code:
var nodes = [];
function getElementById(node, id) {
alert(nodes.length);
if (node.childNodes[i].id == id) {
return node.childNodes[i];
} else if (node.childNodes[i].length > 0) {
for (var i = 0, len = node.childNodes.length; i < len; ++i) {
nodes.push(node.childNodes[i]);
}
}
if (nodes.length > 0) {
getElementById(nodes[0], id);
}
}
var el = getElementById(document.body, 'id');
Any help?

Answer 1

You're missing a for loop in the top half of your code. Where is i defined?
Here's how I'd write it:
function getElementById(node, id) {
//An array of all the nodes at the same depth
var nodes = [node];
//While the array is not empty
while(nodes.length) {
var newNodes = [];
for(var i = 0; i < nodes.length; i++) {
var children = nodes[i].childNodes;
for(var j = 0; j < children.length; j++) {
var child = children[j];
if(child.id == id) {
return child
}
newNodes.push(child);
}
}
//Replace nodes with an array of the nodes the next level down
nodes = newNodes
}
}