7 ES6 Features all JavaScript Programmers Should Learn to Use

let oldArray = [1, 2, 3];let first = oldArray[0]; // first = 1let second = oldArray[1]; // second = 2let third = oldArray[2]; // third = 3let newArray = [1, 2, 3];let [first, second, third] = newArray;// The same operation reduced to just one line

const oldMe = {    name: "kingsley",    sex: "male",    age: 21};const oldName = oldMe.name; // "kingsley"const oldSex = oldMe.sex; // "male"const oldAge = oldMe.age; // 21const newMe = {    name: "kingsley",    sex: "male",    age: 21};{ name, sex, age } = newMe; // Refactored to just one single line

/* BEFORE */function withoutDefault(param1, param2) {    if (param2 === undefined) {        param2 = "second string";    }    console.log(param1, param2);}withoutDefault("first string", "second string");// "first string" and "second string"/* WITH DEFAULT PARAMETER */function withDefault(param1, param2 = "second string") {    console.log(param1, param2);}withDefault("first string");// "first string" and "second string"withDefault("first string", "second string");// Outputs: "first string" and "second string"

// capitalize.jsfunction capitalize(word) {    return word[0].toUpperCase() + word.slice(1);}export { capitalize }; // Exports the function// warn.jsimport { capitalize } from './capitalize'; // Imports the functionfunction warn(name) {    return `I am warning you, ${capitalize(name)}!`;}warn('kingsley');// I am warning you, Kingsley!

var name = "kingsley";var sex = "male";var age = 21;// Using Object Literal Enhancementvar me = {name, sex, age};console.log(me);/*   {     name: "kingsley",     sex: "male",     age: 21   }

var name = "kingsley";var sex = "male";var age = 21;// Functionlet sayName = function (){  console.log(`I am ${this.name}!`);}// With Object Literal Enhancementvar me = {name, sex, age, sayName};me.sayName();// "I am kingsley!"

const successPromise = new Promise((resolve, reject) => {  setTimeout(() => {    resolve('successful!');  }, 300);});// CONTINUATION AFTER 3 SECONDSsuccessPromise.then(value => { console.log(value) })  // "successful!".catch(error => { console.log(error) })--------------------------------------------------------const failPromise = new Promise((resolve, reject) => {  setTimeout(() => {    reject('oops!, something went wrong');  }, 300);});// CONTINUATION AFTER 3 SECONDSfailPromise.then(value => { console.log(value) }) .catch(error => { console.log(error) }) // oops, something went wrong

let name = "kingsley"let age = 21let blog = "ubahthebuilder.tech"function showBlog() {console.log(`My name is ${name}, I am ${age} years old and I blog at ${blog}`);} showBlog();// "My name is kingsley, I am 21 years old and I blog at ubahthebuilder.tech"

let sayName = () => {  return "I am Kingsley";}let sayName2 = (name) => `I am ${name}`;let sayName3 = name => `I am ${name}`; // You can remove the bracketslet sayNameAge = (name, age) => `I am ${name}, and I am ${age} years old`// If argument is more than one, you must wrap in parenthesis