Javascript size on binary search tree -

i have done c++ because can pass in parameter reference. having trouble figuring out how in javascript. need change in code? output 1

this.sizeofbst = function(){     size = 0;      return sizehelper(this.root, size); }  function sizehelper(node, size){     if(node){         sizehelper(node.left, size);         size++;         sizehelper(node.right, size);     }     return size } 

numbers cannot passed reference in javascript. instead, have sizehelper return size , add size total.

function sizehelper(node) {     if (node) {         return 1 + sizehelper(node.left) + sizehelper(node.right);     }     return 0; } 

then can used like

this.sizeofbst = function() {     return sizehelper(this.root); }