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@zeusdeux
Last active September 6, 2023 15:03
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ES5 inheritance vs ES6 inheritance
/* ES6/ES2015 classes */
class A {
constructor() {
this.a = 10
}
print() {
console.log(this.a, this.b)
}
}
class B extends A {
constructor() {
super()
this.b = 20
}
}
/* ES5 equivalent */
function C() {
this.c = 100
}
C.prototype.print = function() {
console.log(this.c, this.d)
}
function D() {
/*
* Same as C.call(this) since we later do D.prototype = Object.create(C.prototype)
*/
Object.getPrototypeOf(D.prototype).constructor.call(this)
this.d = 200
}
D.prototype = Object.create(C.prototype)
let a = new A()
let b = new B()
let c = new C()
let d = new D()
b.print() // outputs 10 20
@zeusdeux
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I use the getPrototypeOf as prototype property can be overwritten. It is also the way babel and other transpilers did this before we had native class syntax in JS engines

@marlonry
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marlonry commented Mar 10, 2021

Object.getPrototypeOf(D.prototype).constructor.call(this) can be simplize like this:

D.prototype.constructor.call(this);

It still works well

I think this throws an error cause you are basically calling Ds constructor not Cs constructor. Maybe explain better how you are getting it to work.

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