Nathans JS lessons 1 - count tree using recursion and iteration

CountTree.js

/*
var count = function(tree) {
    if(!tree) {
        return 0;
    }
    
    return 1 + count(tree.left) + count(tree.right);              
};
*/

var count = function(tree) {
    var nodes = [];
    var count = 0;
    var currentNode;
    
    if(tree) {
        nodes.push(tree);
    }
    
    while(nodes.length) {
        currentNode = nodes.shift();
        count += 1;
        if(currentNode.left) {
            nodes.push(currentNode.left);
        }
        if(currentNode.right) {
            nodes.push(currentNode.right);
        }
    }
    
    return count;
};