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February 14, 2018 13:25
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Showing Inheritance using Object.create and `new` Operator
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| // Shape - superclass | |
| function Shape() { | |
| this.x = 0; | |
| this.y = 0; | |
| } | |
| // Superclass method | |
| Shape.prototype.move = function(x, y) { | |
| this.x += x; | |
| this.y += y; | |
| console.info('Shape moved.'); | |
| }; | |
| // Rectangle - subclass | |
| function Rectangle() { | |
| // If we use new Shape() then properties are assigned in __proto__ | |
| // and still eveything will work.So no need to call Shape.call(this). | |
| // But if we use Object.create(Shape.prototype) then properties x & y are not copied so | |
| // we need to call Shape.call(this). | |
| Shape.call(this); // call super constructor. | |
| } | |
| // subclass extends superclass | |
| //Rectangle.prototype = new Shape(); // <-- This line doesn't require Shape.call(this); | |
| Rectangle.prototype = Object.create(Shape.prototype); | |
| Rectangle.prototype.constructor = Rectangle; | |
| var rect = new Rectangle(); | |
| // Do notice rect in console for right understanding. | |
| var rect = new Rectangle(); | |
| console.log(rect); | |
| console.log(rect.move(1,2)); |
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Some Links that I found useful :
JS Bits
A drip of JavaScript
Object.assign