2018-06-02 How to do inheritance in JS

JS is incredibly flexible. This is a quick recipe for OOP people.

The old way:
demo

function Printer() {
  this.objectType = 'Printer'
  this.print = function print(sth) {
    console.log(sth)
  }
}

function ColorPrinter() {
  Printer.apply(this)
  this.printInRed = function print(sth) {
    console.log('IN RED: ' + sth)
  }
}

ColorPrinter.prototype = Object.create(Printer.prototype)
ColorPrinter.prototype.constructor = ColorPrinter

const colorPrinterA = new ColorPrinter()
console.log(colorPrinterA.objectType)
colorPrinterA.print('document 1')
colorPrinterA.printInRed('document 2')

/**
 *  you will see the following output
    Printer
    document 1
    IN RED: document 2
 */

The modern(es6) way
demo

class Printer {
  constructor() {
    this.objectType = 'Printer'
  }
  print(sth) {
    console.log(sth)
  }
}

class ColorPrinter extends Printer {
  printInRed(sth) {
    console.log('IN RED: ' + sth)   
  }
}

const colorPrinterA = new ColorPrinter()
console.log(colorPrinterA.objectType)
colorPrinterA.print('document 1')
colorPrinterA.printInRed('document 2')

/**
 *  you will see the following output
    Printer
    document 1
    IN RED: document 2
 */