Object assign with dynamic variable

Question

I have this initialState in my Redux store:

const initialState = {
  isFetching : false,
  active     : {}
}

Where active is an object.

Now I have an action that should append or add a property to active’s data property, like so:

[DASHBOARD_TEMPLATE_DATA_RECEIVE]: (state, action) => {
    return Object.assign({}, state, {
      isFetching   : false,
      active       : Object.assign({}, active, {data[action.key]: action.data})
    })
}

As you can see, data[action.key] is not permitted. How do I do it?

score 8 · Accepted Answer · answered Jul 13 '16 at 15:51

8

Try with this:

active: Object.assign({}, active, {
  data: Object.assign({}, data, {
    [action.key]: action.data
  })
})

answered Jul 13 '16 at 15:51

Iso

3,148
23
31

score 1 · Answer 2 · answered Jul 13 '16 at 15:51

1

Build the object up first, making use of square bracket notation to use a string as a property name:

var data = {};
data[action.key] = action.data;

then use that newly created object:

[DASHBOARD_TEMPLATE_DATA_RECEIVE]: (state, action) => {
    return Object.assign({}, state, {
      isFetching   : false,
      active       : Object.assign({}, active, data)
    })
}

answered Jul 13 '16 at 15:51

Jamiec

133,658
13
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I think it should be: `active : Object.assign({}, active, { data })` – Joey Hipolito Jul 14 '16 at 11:18
@JoeyHipolito, perhaps if that is something specific to Redux, for which im not familiar. But in vanilla javascript, `data` is already an object, so no need to surrpound it with `{}`. – Jamiec Jul 14 '16 at 11:19
In-fact, ```data[action.key] = action.data;``` was way helpful if we want to add multiple nodes before hand. Thanks @Jamiec – PravyNandas Jan 20 '20 at 23:20

score 1 · Answer 3 · answered Jul 13 '16 at 15:53

1

I would guess a computed property name might work.

Untested:

active: Object.assign({}, active, {[data[action.key]]: action.data})

answered Jul 13 '16 at 15:53

Ben Aston

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Object assign with dynamic variable

3 Answers3