Recursion down DOM tree

Question

This is code from Crockford\'s JavaScript: The Good Parts.

var results = [];

var walkDOM = function (node,func) {
        func(node);                     //         


        

Answer 1

Crockford's code is passing a callback to walkDOM which can be used in many ways to process the arguments passed to it.

An example could be a method which returns the count of all DOM elements with the specified tagName:

var getTagNameCount = function(tagName) {
    var count = 0;
    walkDOM(document.body, function(node) {
       if (node.tagName === tagName) {
          count++;
       }
    });
    return count;
};