How to describe the type of a dictionary in typescript efficiently?

How to describe the type of a dictionary in typescript more efficient, than the solution below?

type DictEntry = { [key: string]: string }
type UploadDict = { [key: string]: DictEntry }

const UPLOAD_TYPE_DICT: UploadDict = {
  JPG: {
    label: "jpg",
    type: "image/jpeg",
  },
  PNG: {
    label: "png",
    type: "image/png",
  },
}

>Solution :

If you mean a cleaner syntax with more efficiently use Record.

type DictEntry = Record<string, string>
type UploadDict = Record<string, DictEntry>

const UPLOAD_TYPE_DICT: UploadDict = {
  JPG: {
    label: "jpg",
    type: "image/jpeg",
  },
  PNG: {
    label: "png",
    type: "image/png",
  },
}