TreeReduce.js

/**
 * ============== About Reduce Method =====================
 *  The reduce() method executes a callback
 * on each value in a collection. It passes an accumulator
 * and the value of the current value to the callback
 * and updates the accumulator with the returned value
 * resulting in a single output value.
 *
 * Here are two examples of how the reduce method works on an array:
 *
 * ---Example #1---
 * var arr = [2, 3, 4]
 *
 * var cb = function (accumulator, currentValue){
 * return accumulator + (currentValue*2)
 * }
 *
 *  arr.reduce(cb, 1) //19
 * // 1+(2*2) >>> 5+(3*2) >>> 11+(4*2) >>> 19
 *
 *
 * ---Example #2---
 * var arr = [2, 3, 4]
 *
 * var cb = function (accumulator, currentValue){
 * return accumulator + currentValue
 * }
 *
 * arr.reduce(cb) //9
 * // 2+3 >>> 5+4 >>> 9
 *
 *
 *  ================== Prompt =========================
 *
 * Implement a `reduce` method for this Tree class,
 * in the ES6 pseudo-classical instantiation style.
 *
 * Add any other methods or properties necessary to
 * make the example code produce the desired output
 * and run without errors.
 *
 * The `reduce` method should accept two arguments:
 * 1. (required) a callback function which will produce
 *    the accumulated result
 * 2. (optional) a starting value for the accumulation
 *
 * Make sure you do not modify the original tree.
 *
 *
 *
 *
 */

var Tree = function (value) {
  this.value = value;
  this.children = [];
};

// TODO: COMPLETE THESE METHODS
Tree.prototype.addChild = function (value) {
  var child = new Tree(value);
  this.children.push(child);
  return child;
};

Tree.prototype.reduce = function (callback, accumulator) {};

// // Example setup:

// var root = new Tree(0),
//   child1 = root.addChild(1),
//   child2 = child1.addChild(2),
//   child3 = root.addChild(3),
//   child4 = child3.addChild(4),
//   child5 = child3.addChild(5),
//   child6 = root.addChild(6);

// // Example usage:

// root.reduce(function (accumulator, currentValue) {
//   return accumulator + ' ' + currentValue + ',';
// }, 'Values, depth-first:');

// // => "Values, depth-first: 0, 1, 2, 3, 4, 5, 6,"

// root.reduce(function (accumulator, currentValue) {
//   return accumulator + currentValue;
// }); // => 21

// root.reduce(function (accumulator, currentValue) {
//   return accumulator + currentValue;
// }, 10); // => 31