Call setter dynamically from Javascript constructor

Question

I want to configure object via constructor, like that:

class Foo {
  constructor(obj) {
    this.options = {};
    Object.entries(obj).forEach(([key, val]) => {
      const desc = Object.getOwnPropertyDescriptor(this, key);
      if (desc && desc.set) {
        // can't reach that condition
        this[key] = val;
      } else {
        // all properties sets via that condition
        this.options[key] = val;
      }
    });
  }
  set bar(val) {
    this.options.bar = val.toString();
  }
  set baz(val) {
    this.options.baz = parseInt(val, 10);
  }
}

const f = new Foo({ bar: 10, baz: '20', xxx: 0 });
console.log(f.options);
// expected: { bar: '10', baz: 20, xxx: 0 }
// actual { bar: 10, baz: '20', xxx: 0 }

Is it possible to make it works? All properties sets via this.options[key], but I expect that bar and buz should be set via this[key]`.

Hi, @CertainPerformance. I've updated my question to be more specific. — ZhukovRA, Jul 06 '18 at 08:23
See other dupe - `getOwnPropertyDescriptor` doesn't work because the setter is on the *prototype*, not the instantiated object (`this`) itself. Use `const desc = Object.getOwnPropertyDescriptor(Foo.prototype, key);` — CertainPerformance, Jul 06 '18 at 08:30

score 2 · Accepted Answer · answered Jul 06 '18 at 08:03

2

I think the syntax to do this would be (untested)

this[key] = val;

answered Jul 06 '18 at 08:03

martincarlin87

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Hi, I've updated the question. – ZhukovRA Jul 06 '18 at 08:21

Call setter dynamically from Javascript constructor

1 Answers1