Readonly value vs property

⬅️ FEM TypeScript Fundamentals

Readonly value vs property

 
// can't replace it, but can mutate it
type User = {
  name: string
  readonly catNames: string[]
};
 
// can't mutate the array, but can replace it
type User = {
  name: string
  catNames: ReadonlyArray<string>
};
 
// safest
type User = {
  name: string
  readonly catNames: ReadonlyArray<string>
};