How to create an array of objects with different indicies in the React state

Question

I am trying to create an array (todos) with the same objects in the state of my React Component. The object is supposed to consist of an active:false, value and its index.

I tried this:

this.state = {
      todos:Array(15).fill({active:false},{idx:???})
}

What do I write as the index?

Andrew · Accepted Answer · 2018-01-12 01:12:57Z

1

You can skip .fill by spreading Array(15) into an array and then you can just .map. But why are you making an empty array first if you already have values that you want to populate?

[...Array(15)].map((_, idx) => {
  return {active: false, idx}
})

edited Jan 12, 2018 at 1:12

answered Jan 12, 2018 at 1:06

Andrew

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2 Comments

Tom Over a year ago

oh, i have exactly 15 todos and only need to update their status. So I thought I'm creating them in the constructor and then just update their status based on their index. Is that correct ?

Andrew Over a year ago

Made a syntax mistake. Above works. As long as your implementation works, then by all means use it.

Sergii Rudenko · Accepted Answer · 2018-01-12 01:00:22Z

1

You can write an index in array as idx to the object:

Array(15).fill({ active: false }).map((i, k) => ({ ...i, ...{ idx: k }}));

But you need to use map to iterate throw array one more time and create a new array with indexes.

answered Jan 12, 2018 at 1:00

Sergii Rudenko

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