Can't assign this in constructor

Question

I'm trying to merge the props from values into this.

The following throws an error. How can I do this?

this = {...this, ...values}

I think that's trying to create a new object and assign it to `this`, not merging properties into `this`. — Barmar, Apr 27 '16 at 18:06
`this` is a reserved javascript word and cannot be overwrote, have you tried using a different var name? — Derek Pollard, Apr 27 '16 at 18:06
`this` is unassignable. what are you **really** trying to do? — Amit, Apr 27 '16 at 18:07
I think he's trying to do the equivalent of jQuery's`$.extend(this, values)`. — Barmar, Apr 27 '16 at 18:07

score 32 · Accepted Answer · answered Apr 27 '16 at 18:10

32

You could extend this with Object.assign method:

class Foo {
  constructor (props) {
    Object.assign(this, props);
  }
}

const foo = new Foo({ a: 1 });
console.log(foo.a); // 1

answered Apr 27 '16 at 18:10

Роман Парадеев

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score 1 · Answer 2 · edited Sep 07 '17 at 14:26

Seeing your use of the spread operator, it looks like you're using a Stage 3 proposal for ECMAScript.

https://github.com/tc39/proposal-object-rest-spread

Try the Object.assign method:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign

The Object.assign() method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object.

Object.assign(target, ...sources);

Can't assign this in constructor

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