使用递归打印出BST的值-javascript

Question

I'm trying to understand recursion better in Javascript with this code for a BST. I can print out a BST's values with two methods using recursion, but I can't figure out how to do it all in one method.

how can I combine

 BinarySearchTree.prototype.dfs = function(node) { if (node) { console.log(node.val); this.dfs(node.left); this.dfs(node.right); } } BinarySearchTree.prototype.depthFirstTraversal = function() { let current = this.root; this.dfs(current); } 

into one function? I've been trying

 BinarySearchTree.prototype.sameFunction = function(node = null) { // if node is null use this.root let current = node || this.root; if (current) { console.log(current.val); this.sameFunction(current.left); this.sameFunction(current.right); } } 

http://jsfiddle.net/rj2tyd4L/

Answer 1

What about using a second argument isRoot with it's default value set to true ?

BinarySearchTree.prototype.sameFunction = function(node = null, isRoot = true) {
  let current = isRoot ? this.root : node;
  if (current) {
    console.log(current.val);
    this.sameFunction(current.left, false);
    this.sameFunction(current.right, false);
  }
}

http://jsfiddle.net/fez1jtsx/

This makes tree.sameFunction() equivalent to calling tree.depthFirstTraversal()