JavaScript Certification

Author: SamarthMule

1) Basic JavaScript.js

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+// Compare Scopes of the var and let Keywords
+function checkScope() {
+"use strict";
+  let i = "function scope";
+  if (true) {
+    let i = "block scope";
+    console.log("Block scope i is: ", i);
+  }
+  console.log("Function scope i is: ", i);
+  return i;
+}
+
+// Mutate an Array Declared with const
+const s = [5, 7, 2];
+function editInPlace() {
+  "use strict";
+  s[0] = 2;
+  s[1] = 5;
+  s[2] = 7;
+}
+editInPlace();
+
+// Prevent Object Mutation
+function freezeObj() {
+  "use strict";
+  const MATH_CONSTANTS = {
+    PI: 3.14
+  };
+  Object.freeze(MATH_CONSTANTS);
+  try {
+    MATH_CONSTANTS.PI = 99;
+  } catch(ex) {
+    console.log(ex);
+  }
+  return MATH_CONSTANTS.PI;
+}
+
+// Use Arrow Functions to Write Concise Anonymous Functions
+const magic = () => new Date();
+
+// Write Arrow Functions with Parameters
+const myConcat = (arr1, arr2) => arr1.concat(arr2);
+
+// Set Default Parameters for Your Functions
+const increment = (number, value = 1) => number + value;
+
+// Use the Rest Parameter with Function Parameters
+const sum = (...args) => args.reduce((a, b) => a + b, 0);
+
+// Use the Spread Operator to Evaluate Arrays In-Place
+const arr1 = ['JAN', 'FEB', 'MAR', 'APR', 'MAY'];
+let arr2;
+(function() {
+  "use strict";
+  arr2 = [...arr1];
+})();
+console.log(arr2);
+
+// Use Destructuring Assignment to Extract Values from Objects
+const HIGH_TEMPERATURES = {
+  yesterday: 75,
+  today: 77,
+  tomorrow: 80
+};
+const {today, tomorrow} = HIGH_TEMPERATURES;
+
+// Use Destructuring Assignment to Assign Variables from Objects
+const HIGH_TEMPERATURES0 = {
+  yesterday: 75,
+  today: 77,
+  tomorrow: 80
+};
+
+// Use Destructuring Assignment to Assign Variables from Objects
+const {today: highToday4, tomorrow: highTomorrow} = HIGH_TEMPERATURES;
+
+// Use Destructuring Assignment to Assign Variables from Nested Objects
+const LOCAL_FORECAST = {
+    yesterday: { low: 61, high: 75 },
+    today: { low: 64, high: 77 },
+    tomorrow: { low: 68, high: 80 }
+  };
+
+const {today: {low: lowToday, high: highToday}} = LOCAL_FORECAST;
+
+// Use Destructuring Assignment to Assign Variables from Arrays
+let a = 8, b = 6;
+(() => {
+  "use strict";
+  [a, b] = [b, a];
+})();
+console.log(a);
+
+// Use Destructuring Assignment with the Rest Parameter to Reassign Array Elements
+const source = [1,2,3,4,5,6,7,8,9,10];
+function removeFirstTwo(list) {
+"use strict";
+  const [a, b, ...arr] = list;
+  return arr;
+}
+const arr = removeFirstTwo(source);
+
+// Use Destructuring Assignment to Pass an Object as a Function's Parameters
+const stats = {
+  max: 56.78,
+  standard_deviation: 4.34,
+  median: 34.54,
+  mode: 23.87,
+  min: -0.75,
+  average: 35.85
+};
+const half = ({max, min}) => (max + min) / 2.0;
+console.log(half(stats));
+
+// Create Strings using Template Literals
+const result = {
+  success: ["max-length", "no-amd", "prefer-arrow-functions"],
+  failure: ["no-var", "var-on-top", "linebreak"],
+  skipped: ["no-extra-semi", "no-dup-keys"]
+};
+function makeList(arr){
+"use strict";
+  const resultDisplayArray = arr.map(item => `<li class="text-warning">${item}</li>`);
+  return resultDisplayArray;
+}
+const resultDisplayArray = makeList(result.failure);
+
+// Write Concise Object Literal Declarations Using Object Property Shorthand
+const createPerson = (name, age, gender) =>{
+  return {
+    
+  }
+}
+
+// Write Concise Declarative Functions with ES6
+const bicycle = {
+  gear: 2,
+  setGear(newGear) {
+    this.gear = newGear;
+  }
+};
+
+// Use class Syntax to Define a Constructor Function
+class Vegetable {
+  constructor(name){
+    this.name = name;
+  }
+}
+
+const carrot = new Vegetable('carrot');
+console.log(carrot.name);
+
+// Use getters and setters to Control Access to an Object
+class Thermostat {
+  constructor(fahrenheit){
+    this.fahrenheit = fahrenheit;
+  }
+  get temperature(){
+    return 5/9 * (this.fahrenheit - 32);
+  }
+  set temperature(celsius){
+    this.fahrenheit = celsius * 9.0 / 5 + 32;
+  }
+}
+
+const thermos = new Thermostat(76);
+let temp = thermos.temperature;
+thermos.temperature = 26;
+temp = thermos.temperature;
+
+// Create a Module Script
+<html>
+  <body>
+<script type="module" src="index.js"></script>
+
+  </body>
+</html>
+
+// Use export to Share a Code Block
+const uppercaseString = (string) => {
+  return string.toUpperCase();
+}
+
+const lowercaseString = (string) => {
+  return string.toLowerCase()
+}
+
+export { uppercaseString, lowercaseString };
+
+// Reuse JavaScript Code Using import
+import { uppercaseString, lowercaseString } from './string_functions.js';
+uppercaseString("hello");
+lowercaseString("WORLD!");
+
+// Use * to Import Everything from a File
+import * as stringFunctions from "./string_functions.js";
+stringFunctions.uppercaseString("hello");
+stringFunctions.lowercaseString("WORLD!");
+
+// Create an Export Fallback with export default
+export default function subtract(x, y) {
+  return x - y;
+}
+
+// Import a Default Export
+import subtract from "./math_functions.js";
+subtract(7,4);
+
+// Create a JavaScript Promise
+const makeServerRequest = new Promise((resolve, reject) => {});
+
+// Complete a Promise with resolve and reject
+const makeServerRequest8 = new Promise((resolve, reject) => {
+  let responseFromServer = true;
+  if(responseFromServer){
+    resolve("We got the data");
+  } else {
+    reject("Data not received");
+  }
+});
+
+// Handle a Fulfilled Promise with then
+const makeServerRequest4 = new Promise((resolve, reject) => {
+  let responseFromServer = true;
+  if(responseFromServer){
+    resolve("We got the data");
+  } else {
+    reject("Data not received");
+  }
+});
+makeServerRequest.then(result => {
+  console.log(result);
+});
+
+// Handle a Rejected Promise with catch
+const makeServerRequest2 = new Promise((resolve, reject) => {
+  let responseFromServer = false;
+  if(responseFromServer){
+    resolve("We got the data");
+  } else {
+    reject("Data not received");
+  }
+});
+makeServerRequest.then(result => {
+  console.log(result);
+});
+makeServerRequest.catch(error => {
+  console.log(error);
+});
+