San Francisco Bay Area Professional Blog: Traverse/walk DOM tree recursively

San Francisco Bay Area Professional Blog: Traverse/walk DOM tree recursively

Traverse/walk DOM tree recursively

Task definition: You have a DOM tree (startNode which can be the whole document), and need to find first specific tag in this tree.

Here is the recursion function to do this:

1. function findNodeByTag(startNode, tagName) {
2.     if (startNode.nodeName.toLowerCase() == tagName.toLowerCase()) return startNode;
3.     var childList = startNode.childNodes;
4.     for (var i=0; i<childList.length; i++) {
5.         return findNodeByTag(childList[i], tagName);
6.     }
7.     return null;
8. }

And you call it:

1. findNodeByTag(myDOMobj, "img");