How to add one more value to an array of objects, to each object?

Question

JavaScript

I have an array of object:

[
  {
    "id": "1",
    "title": "Дом1"
  },
  {
    "id": "2",
    "title": "Зал2"
  },
  {
    "id": "3",
    "title": "Дом3"
  },
  {
    "id": "4",
    "title": "Зал4"
  }
]

Need an array of object:

[
  {
    "id": "1",
    "title": "Дом1",
    "active": "true"
  },
  {
    "id": "2",
    "title": "Зал2",
    "active": "false"
  },
  {
    "id": "3",
    "title": "Дом3",
    "active": "false"
  },
  {
    "id": "4",
    "title": "Зал4",
    "active": "false"
  }
]

When trying on typescript, Angular 4 throws this error:

Error:
ERROR TypeError: Cannot set property 'active' of undefined

Answer 1

map
forEach?

var a = [{
      "id": "1",
      "title": "Дом1"
    }, {
      "id": "2",
      "title": "Зал2"
    }, {
      "id": "3",
      "title": "Дом3"
    }, {
      "id": "4",
      "title": "Зал4"
    }];
    for (let i of a) {
      i.active = false;
    }
    console.log(a);

Answer 2

arr.forEach((obj) => obj['active'] = false);