CODEWITHSUNDEEP
typescript
gcr
gcr

Reputation: 463

Declaring object of arrays in Typescript; getting error Type '{}' missing the following properties

I have the following code:

  const qn = props.question.question // == question number
  const statusLib: { [index: number]: {} } = {
    82: ["70%", "0%", "0%", 1, 1],
    83: ["70%", "0%", "0%", 1, 2],
    84: ["100%", "45%", "0%", 2, 3],
    85: ["100%", "70%", "0%", 2, 3],
    86: ["100%", "100%", "46%", 3, 3],
  }
  const s:Array<ReactText> = statusLib[qn] // squiggly under 's'. Should return array

I want to keep it short and sweet. This should be min reproducible example. I tried various permutations, with about the same result.

I never had a problem rendering on local server. It's strictly a typescript enforcement thing.

Type '{}' is missing the following properties from type 'any[]': length, pop, push, concat, and 28 more.ts(2740)

I'm still learning the semantics of TS but my understanding is from this const statusLib: { [index: number]: {} } = {

you're declaring how the the object should be indexed, and then that it is an object of the most general type.

My assignment s = ... obviously returns an array. If I wasn't my code wouldn't work at all. Typescript thinks it's an object, so maybe I'm accidentally telling it that. I tried various ways to tell it all the contents are arrays such as :

const statusLib: { [index: number]: {[]} } = { and s:any[]

StatusLib is an object indeed but it's children are all arrays. How do I tell TS this?

Upvotes: 1

Views: 1293

Answers (2)

Beshambher Chaukhwan
Beshambher Chaukhwan

Reputation: 1448

You are telling TS that your statusLib is an object {} with key value pairs of type number: object but then you actually need them as number: array this the error that it expects object index: {} but instead its getting index: []. Try the following

const statusLib: { [index: number]: Array<string | number> }

Upvotes: 1

k0pernikus
k0pernikus

Reputation: 66490

You have an array like ["70%", "0%", "0%", 1, 1] that you typehint as an empty object {}. You at least need an array [], which could be any[] (worst), unknown[] (still bad), (string|number)[] (getting close), yet since your array is consistent it seems to be a tuple that you could type in the form of:

type MyTuple = [string, string, string, number, number];

Then your typing should become

 const statusLib: { [index: number]: MyTuple }

(You don't need the custom type defintion. It may be useful in the long run.)

Upvotes: 2

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