Given multiple plausible reasons, identify why functions are called “First Class Objects” in JavaScript. Given a code snippet containing an anonymous callback, a named callback, and multiple console.logs, predict what will be printed Write a function that takes in a value and two callbacks. The function should return the result of the callback that is greater. Write a function, myMap, that takes in an array and a callback as arguments. The function should mimic the behavior of Array#map. Write a function, myFilter, that takes in an array and a callback as arguments. The function should mimic the behavior of Array#filter. Write a function, myEvery, that takes in an array and a callback as arguments. The function should mimic the behavior of Array#every.
// 1. Given multiple plausible reasons, identify why functions are called “First Class Objects” in JavaScript. // Here are some of the reasons: // A function is an instance of the Object type // You can store the function in a variable let negate = function (num) { return num _ -1; }; // You can pass the function as a parameter to another function function player(callback) { console.log(‘Lebron’); callback(); } player(function () { console.log(‘Los Angeles’); }); // You can return the function from a function function sport() { return (function team() { return “I’m a returned function” }) } let newFunc = sport(); console.log(newFunc()) // 2. Given a code snippet containing an anonymous callback, a named callback, and multiple console.logs, predict what will be printed function player(callback) { console.log(‘Lebron’); callback(); } function sport() { console.log(‘Basketball’); } const teamInfo = function () { console.log(‘Lakers’); sport(); player(sport); player(function () { console.log(‘Los Angeles’); }); console.log(‘California’); }; teamInfo(); // 3. Write a function that takes in a value and two callbacks. The function should return the result of the callback that is greater. function greaterValue(value, cb1, cb2) { // compare cb1 invoked with value to cb2 invoked with value // return the greater result let res1 = cb1(value); let res2 = cb2(value); if (res1 > res2) { // if this is false, we move out of if statement return res1; } return res2; } let negate = function (num) { return num _ -1; }; let addOne = function (num) { return num + 1; }; console.log(greaterValue(3, negate, addOne)); console.log(greaterValue(-2, negate, addOne)); // 4. Write a function, myMap, that takes in an array and a callback as arguments. The function should mimic the behavior of Array#map. function myMap(arr, callback) { // iterate through the array, perform the cb on each element // return a new array with those new values let mapped = []; for (let i = 0; i < arr.length; i++) { // remember that map passes three args with each element. let val = callback(arr[i], i, arr); mapped.push(val); } return mapped; } let double = function (num) { return num _ 2; }; console.log(myMap([1, 2, 3], double)); // 5. Write a function, myFilter, that takes in an array and a callback as arguments. The function should mimic the behavior of Array#filter. function myFilter(arr, callback) { let filtered = []; for (let i = 0; i < arr.length; i++) { let element = arr[i]; if (callback(element, i, arr)) { filtered.push(element); } } return filtered; } // 6. Write a function, myEvery, that takes in an array and a callback as arguments. The function should mimic the behavior of Array#every. function myEvery(arr, callback) { for (let i = 0; i < arr.length; i++) { let element = arr[i]; if (callback(element, i, arr) === false) { return false; } } return true; } // Initialize calculation functions to variables to put in array. let add = function (n1, n2) { return n1 + n2; }; let subtract = function (n1, n2) { return n1 - n2; }; let multiply = function (n1, n2) { return n1 _ n2; }; let divide = function (n1, n2) { return n1 / n2; }; let mod = function (n1, n2) { return n1 % n2; }; let isDivisible = function (n1, n2) { if (mod(n1, n2) === 0) { return true; } return false; }; // Initialize array containing calculation functions let funcArray = [add, subtract, multiply, divide, mod, isDivisible]; // Initialize function taking two numbers and an array // of functions as parameters let calculateAll = function (n1, n2, arrayOfFuncs) { let ansArray = []; arrayOfFuncs.forEach(function (callback) { ansArray.push(callback(n1, n2)); }); return ansArray; }; // Initialize a function taking two numbers, an array // of functions, and a users choice of which to call // as parameters let calculateChosen = function (n1, n2, arrayOfFuncs, choice) { return arrayOfFuncschoice; }; // Call the function, passing in 10, 2, and an // array of functions console.log(calculateAll(10, 2, funcArray)); // Call the function, passing in 10, 2, and the // users choice of operation console.log(calculateChosen(10, 2, funcArray, 1));