inheritance.js

   1 function Base(x, y)\r
   2 {\r
   3     this.x = x;\r
   4     this.y = y;\r
   5     console.log('Base here', this.x, this.y);\r
   6 }\r
   7 \r
   8 Base.prototype.echo = function()\r
   9 {\r
  10     console.log('Base echo here', this.x, this.y);\r
  11 };\r
  12 \r
  13 function Derived(x, y, z)\r
  14 {\r
  15     console.log('calling base');\r
  16     Base.call(this, x, y);\r
  17     console.log('base called');\r
  18     this.z = z;\r
  19     console.log('Derived here', this.x, this.y, this.z);\r
  20 }\r
  21 \r
  22 Derived.prototype = new Base; // Base constructor null null is called\r
  23 Derived.prototype.base = Base.prototype;\r
  24 \r
  25 Derived.prototype.echo = function()\r
  26 {\r
  27     this.base.echo.call(this);\r
  28     console.log('Derived echo here', this.x, this.y, this.z);\r
  29 };\r
  30 \r
  31 var t = new Derived(10, 20, 30);\r
  32 console.log('init complete');\r
  33 t.echo();\r
  34 Derived.constructor.toSource();\r
  35 \r
  36 console.log(t instanceof Base); // true\r
  37 console.log(t instanceof Derived); // true\r
  38 \r