JavaScript

Classes
Modules

Classes

This example declares two classes: Nurse which extends from HospitalEmployee. It also have a static method (callable from the class, not from an instance of the class).

class HospitalEmployee {
  constructor(name) {
    this._name = name;
    this._remainingVacationDays = 20;
  }
  
  get name() {
    return this._name;
  }
  
  get remainingVacationDays() {
    return this._remainingVacationDays;
  }
  
  takeVacationDays(daysOff) {
    this._remainingVacationDays -= daysOff;
  }

  static generatePassword() {
    return Math.floor(Math.random() * 10000);
  }
}

class Nurse extends HospitalEmployee {
  constructor(name, certifications) {
    super(name);
    this._certifications = certifications;
  } 
  
  get certifications() {
    return this._certifications;
  }
  
  addCertification(newCertification) {
    this.certifications.push(newCertification);
  }
}

const nurseOlynyk = new Nurse('Olynyk', ['Trauma','Pediatrics']);
nurseOlynyk.takeVacationDays(5);
console.log(nurseOlynyk.remainingVacationDays);
nurseOlynyk.addCertification('Genetics');
console.log(nurseOlynyk.certifications);
console.log('Your password is ' + HospitalEmployee.generatePassword());

Output:

15
[ 'Trauma', 'Pediatrics', 'Genetics' ]
Your password is 3989

Modules

Export module

This example exports two functions: squareArea and circleArea.

/* shape-area.js */
const PI = Math.PI;

// Define and export circleArea() and squareArea() below
function squareArea(sideLength) {
  return sideLength * sideLength;
}
 
module.exports.squareArea = squareArea;
 
module.exports.circleArea = function(radiusLength) {
  return PI * radiusLength * radiusLength;
};

Import module

Use require to import the whole module:

/* app.js */ 

const radius = 5;
const sideLength = 10;

// Option 1: import the entire shape-area.js module here.
const areaFunctions = require('./shape-area.js');

// use the imported .circleArea() and .squareArea() methods here
// With option 1:
const areaOfCircle = areaFunctions.circleArea(radius);
const areaOfSquare = areaFunctions.squareArea(sideLength);

Or load only what we need with object destructuring:

// Option 2: import circleArea and squareArea with object destructuring
const { circleArea, squareArea } = require('./shape-area.js');

// with option 2:
const areaOfCircle = circleArea(radius);
const areaOfSquare = squareArea(sideLength);

Promise

Example with Promise.all(). All promise have to succeed to launch the onFulfill function.

const {checkAvailability} = require('./library.js');

const onFulfill = (itemsArray) => {
  console.log(`Items checked: ${itemsArray}`);
  console.log(`Every item was available from the distributor. Placing order now.`);
};

const onReject = (rejectionReason) => {
  console.log(rejectionReason);
};

// Write your code below:
const checkSunglasses = checkAvailability('sunglasses', 'Favorite Supply Co.');
const checkPants = checkAvailability('pants', 'Favorite Supply Co.');
const checkBags = checkAvailability('bags', 'Favorite Supply Co.');

Promise.all([checkSunglasses, checkPants, checkBags])
  .then(onFulfill)
  .catch(onReject);

wiKB