Refer to another Object inside own JavaScript Object

Question

I declare Homebrew as a dependency for cask and referred to homebrew by this.homebrew[0]. Is anything like this possible with JavaScript?

var data = {
  homebrew: [
    {
      title: "Homebrew",
      dependencies: [],
      install: function() {
         console.log('homebrew')
      }
    },
    {
      title: "Cask",
      dependencies: [
         this.homebrew[0]
      ],
      install: function() {
         console.log('cask')
      }
    }
  ]
}

data should be an object in your case. Besides, how dependencies is used in further logic ? — RomanPerekhrest
– RomanPerekhrest, Commented Jan 30, 2017 at 21:27
dependencies should image the whole object titled homebrew — André Kuhlmann
– André Kuhlmann, Commented Jan 30, 2017 at 21:32
you can't do it in a single-step object literal - it's possible if you use multiple step initialisation — Alnitak
– Alnitak, Commented Jan 30, 2017 at 21:34

Seiyria · Accepted Answer · 2017-01-30 21:32:55Z

2

This is possible. One thing you can do is create your objects outside of the array, and set up references that way, such as:

var Homebrew = { title: "Homebrew" }
var Cask = { title: "Cask", dependencies: [Homebrew] }
var data = [ Homebrew, Cask ]

answered Jan 30, 2017 at 21:32

Seiyria

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RomanPerekhrest · Accepted Answer · 2017-01-30 21:45:36Z

1

The solution using Javascript get syntax(defining a getter):

var data = {
  homebrew: [
    {
      title: "Homebrew",
      dependencies: [],
      install: function () {
        console.log('homebrew')
      }
    },
    {
      title: "Cask",
      get dependencies() {   //  <-- getter function
        return [data.homebrew[0]]
      },
      install: function () {
        console.log('cask')
      }
    }
  ]
};

console.log(data.homebrew[1].dependencies[0]);

answered Jan 30, 2017 at 21:45

RomanPerekhrest

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3 Comments

Alnitak Over a year ago

I think this is an unsafe approach. If the homebrew array gets rearranged the dependencies property will continue to return the zeroth item, breaking the dependency graph.

Alnitak Over a year ago

It also breaks one of my cardinal rules - that an object should never internally refer to itself by the name of the variable to which it has been assigned.

Alnitak Over a year ago

re: the latter comment, try var x = data; data = {}; console.log(x.homebrew[1].dependencies) - you now have a broken object

Matt Spinks · Accepted Answer · 2017-01-30 21:35:12Z

0

One possibility is to use a separate dependency object.

var data = {
  homebrew: [
    {
      title: "Homebrew",
      dependencies: [],
      install: function() {
         console.log('homebrew')
      }
    },
    {
      title: "Cask",
      dependencies: [
         this.homebrew[0]
      ],
      install: function() {
         console.log('cask')
      }
    }
  ]
};

var dependencies = [
  {
    data.homebrew[0],
    data.homebrew[1]
  }
];

answered Jan 30, 2017 at 21:35

Matt Spinks

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