Typescript object with generic keys and regular keys?

Question

I have the following type:

type MyKeys = 'foo' | 'bar' | 'baz'

I want to define a type that has keys of type MyKeys, but also extends it with more keys, like this:

type FooType = {
  [key in MyKeys]: boolean
  quux: boolean   // <--- Error: '}' expected.ts(1005)
}

How can I use both generic keys and explicit key names?

I'm also not sure if "generic keys" is what you call this, nor if "explicit keys" makes sense — kuceb
– kuceb, Commented Mar 7, 2019 at 16:34

kuceb · Accepted Answer · 2019-03-07 16:29:50Z

2

type FooType = {[key in MyKeys]: boolean} & {
  quux: boolean
}

or as mentioned by @jcalz, you can also use Record<>:

Record<MyKeys | 'quux', boolean>

that will equivalent to:

answered Mar 7, 2019 at 16:24

kuceb

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2 Comments

That's an interesction, not a union.

You can also do Record<MyKeys | 'quux', boolean>