‘as const’ combined with type?

Edit Sep 2022:

With Typescript 4.9 we can now use satisfies operator:

type MyType = { name: string }

const x ={
  name: 'test', // Autocompleted, typesafe
} as const satisfies MyType

x.name // type is 'test' (not string)

And if for some reason, you can’t use satisfies, it’s fairly easy to replicate the same behavior:

/**
 * Replacement for TS satisfies operator, until it's well supported
 * Usage:
 * const test = satisfy<{ a: string }>()({ a: 'test', b: 'test' })
 * */
export function satisfy<TSatisfied>(): <T extends TSatisfied>(value: T) => T {
  return (value) => value
}

Previous solution:

Here is a way to achieve what you want:

type MyType = { name: string }

// This function does nothing. It just helps with typing
const makeMyType = <T extends MyType>(o: T) => o

const x = makeMyType({
  name: 'test', // Autocompleted, typesafe
} as const)

x.name // type is 'test' (not string)