Function and For Loop Demo

loop_function_demo.js

/* =============================================================
  DEMO: create a function that will log all items in an array
================================================================ */

// declare our function
function logItems() {
  // create an array of items
  var items = ['some item', 'another item', 'final item'];

  // loop through each of the items in the array
  for (var i = 0; i < items.length; i++) {
    // log the item name on each iteration of the loop
    console.log(items[i]);
  }
}

// invoke (aka "call") the function
logItems();

/* ==============================================================================
  DEMO: create a function that accepts an array of integers as it's argument
        the function should return a new array with each number multiplied by 2
================================================================================= */

// declare our function with a single parameter
function multiplyNums(arr) {
  // declare a variable who's value is an empty array
  // this empty array will be used to eventually hold our final/new array
  var nums = [];

  // loop through each item in our passed in array
  for (var i = 0; i < arr.length; i++) {
    // multiply the number by 2 on each iteration and push it to our "nums" array
    nums.push(arr[i] * 2);
  };

  // return the new array of multiplied numbers
  return nums;
}

// invoke our function and pass in an array as it's argument
multiplyNums([2, 10, 30]);