rafagarcia

Are your feelings hurt?

If you rushed through David Shariff's JS Quiz or are just new to JS they might be. I know mine were. After I dried my eyes, I took the quiz again, this time very slowly trying to get at the meat behind each answer. Below is my attempt to explain each question's answer and offer some interesting permutations so that others can move beyond their hurt feelings and come out the other side better JS developers.

I initially thought I'd turn this into a blog post but think it's probably better as a gist.

Question #1

Don't over think it.

var foo = function foo() {

rafagarcia

Are your feelings hurt?

If you rushed through David Shariff's JS Quiz or are just new to JS they might be. I know mine were. After I dried my eyes, I took the quiz again, this time very slowly trying to get at the meat behind each answer. Below is my attempt to explain each question's answer and offer some interesting permutations so that others can move beyond their hurt feelings and come out the other side better JS developers.

I initially thought I'd turn this into a blog post but think it's probably better as a gist.

Question #1

Don't over think it.

var foo = function foo() {

rafagarcia

/* Dado el siguiente array de objetos, queremos que se muestre
   en consola el valor agregado de las edades de todos los
   empleados con el valor de position 'engineer'.
*/

let employees = [
  {
    'fullName': 'Andres Urquía',
    'age': 25,
    'position': 'engineer'

rafagarcia

var module = (function(){
    /* simple método privado */
    var privateMethod = function(){
        console.log("soy un método privado");
    };
  
    /* retornando un objeto literal */
    return{
        publicMethod : function(){
            privateMethod();

rafagarcia

Hex Opacity Values

100% — FF
95% — F2
90% — E6
85% — D9
80% — CC
75% — BF
70% — B3
65% — A6

rafagarcia

const numbers = [10, 20, 30, 40];

let updatedNumbers = numbers
                      .map((num) => num * 2)
                      .filter((num) => num > 50);

let doubledOver50 = numbers.reduce((finalList, num) => {
  num = num * 2; //double each number (i.e. map)
  //filter number > 50
  if (num > 50) {

rafagarcia

var cars = ['BMW','Benz', 'Benz', 'Tesla', 'BMW', 'Toyota'];
var carsObj = cars.reduce(function (obj, name) { 
   obj[name] = obj[name] ? ++obj[name] : 1;
  return obj;
}, {});

console.log(carsObj);

rafagarcia

// Destructuring with rest parameter
let {_internal, tooBig, ...cleanObject} = {el1: '1', _internal:"secret", tooBig:{}, el2: '2', el3: '3'};
console.log(cleanObject); // {el1: '1', el2: '2', el3: '3'}

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// Destructuring nested object

var car = {
  model: 'bmw 2018',
  engine: {
    v6: true,
    turbo: true,
    vin: 12345
  }
}

rafagarcia

// sets

let arr = [1, 1, 2, 2, 3, 3];
let deduped = [...new Set(arr)] // [1, 2, 3]

console.log(deduped);

let mySet = new Set([1,2, 3, 4, 5]);
var filtered = [...mySet].filter((x) => x > 3) // [4, 5]