How to create typescript interface for array of objects with array as values

Issue

I have input data in this form:

const input = {
    postcode: ['0000']
    submitted: ['yes']
}

const output = {
    postcode: '0000'
    submitted: 'yes'
}

How to create interface for input data?

I tried:

interface inputData {
    postcode: string[]
    submitted: string[]
}

interface outputData {
    postcode: string
    submitted: string
}

But I get error while applying it:

const extract = (input: inputData[]): outputData => {
  for (const key in input) {
    if (Object.hasOwnProperty.call(input, key)) {
      input[key] = input[key][0]; // Error here
    }
  }
  const output: any = input;
  return output;
}

Error: Element implicitly has an 'any' type because expression of type '0' can't be used to index type 'inputData'. Property '0' does not exist on type 'inputData'.

Solution

You can define an interface with an indexer:

interface EnumServiceGetOrderBy {
    [index: number]: { id: number; label: string; key: any };
}

Answered By - Matte