How to inherit using Object.create()

Question

I created an instance of Shape using Object.create() method and tried accessing the property of Shape as follows, but the inherited property becomes undefined:

    function Shape(){
      this.x = 10;
      this.y = 20;
    }

    var rectangle = Object.create(Shape);

    console.log(rectangle.x) // undefined

[Here's another question which might provide some insight and possible alternatives](https://stackoverflow.com/questions/13040684/javascript-inheritance-object-create-vs-new) — kingdaro, Apr 30 '18 at 03:40
Possible duplicate of [JavaScript inheritance: Object.create vs new](https://stackoverflow.com/questions/13040684/javascript-inheritance-object-create-vs-new) — Alexis King, Apr 30 '18 at 03:43
Your question title is asking about inheritance, but your question body is about making an instance. These are two different things. — Mark, Apr 30 '18 at 03:43
@Mark_M Don't we make instance to inherit from parent objects? — Prem, Apr 30 '18 at 03:46

score 2 · Answer 1 · answered Apr 30 '18 at 03:40

2

To create an instance of a constructor, use new

var rectangle = new Shape()

answered Apr 30 '18 at 03:40

Sebastian Olsen

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Shouldn't we use `Object.create()` to create an instance of a constructor? – Prem Apr 30 '18 at 03:42

score 0 · Answer 2 · answered Apr 30 '18 at 03:55

May declare the shape as an object instead of function though functions are first class object in js. Create a function inside this object and return the required value from this function

var shape = {
  userProperty: function(x, y) {
    this.x = x || 10; // if no value of x is passed it will be 10
    this.y = y || 10; // if no value of y is passed it will be 10
    return {
      x: this.x,
      y: this.y
    }
  }
}
var rectangle = Object.create(shape);
console.log(rectangle.userProperty(40).x) // 40

How to inherit using Object.create()

2 Answers2