sevperez

var myNums = [1, 2, 3, 4, 5];

function doubleNum(num) {
  return num * 2;
}

// Built-in Array.prototype.map function, using anonymous function argument
var doubledNums = myNums.map(function(num) {
  return num * 2;
});

sevperez

function applicator(fn, val) {
  return function() {
    fn(val);
  };
}

function speak(string) {
  console.log(string);
}

sevperez

function speak(string) {
  console.log(string);
}

var delayedFunction = function(fn) {
  return function(val, delay) {
    setTimeout(function() {
      fn(val);
    }, delay);
  };

sevperez

function isPalindrome(str) {
  var reverse = str.split("").reverse().join("");
  return str === reverse;
}

function getCharCounts(chars) {
  var charCounts = {};
  for (var i = 0, charLen = chars.length; i < charLen; i += 1) {
    if (charCounts[chars[i]]) {
      charCounts[chars[i]] += 1;

sevperez

var prices = [400, 80, 375, 870];

// 1
for (var i = 0; i < prices.length; i += 1) {
  console.log(prices[i]);
}
  // logs 400, 80, 375, 870

// 2
for (var k in prices) {

sevperez

var products = { 
  "widget": 400,
  "gear": 80,
  "crank": 375,
  "lever": 870,
};

// 1
var productKeys = Object.keys(products);
for (var i = 0; i < productKeys.length; i += 1) {

sevperez

var prices = [400, 80, 375, 870];

var products = { 
  "widget": 400,
  "gear": 80,
  "crank": 375,
  "lever": 870,
};

var pricesDescriptors = Object.getOwnPropertyDescriptors(prices);

sevperez

var prices = [400, 80, 375, 870];
Object.defineProperty(prices, 1, { enumerable: false });

for (var k in prices) {
  console.log(prices[k]);
}
  // logs 400, 375, 870 ... the 80 is missing!

sevperez

var products = { 
  "widget": 400,
  "gear": 80,
  "crank": 375,
  "lever": 870,
};

Object.defineProperty(products, "gear", { enumerable: false });

// 1

sevperez

var products = { 
  "widget": 400,
  "gear": 80,
  "crank": 375,
  "lever": 870,
};

var otherProducts = Object.create(products);
otherProducts["wheel"] = 210;