How to extract exact union type from object key strings in typescript?

Question

I've got an object like this

const MY_OBJECT = {
  'key': 'key val',
  'anotherKey': 'anotherKey val',
};

Is there a way to extract from this object 'key' | 'anotherKey' type ?

I think the question is more about typescript types .. at least in my reading.. then again everything looks like a nail when you are a hammer :P — Titian Cernicova-Dragomir, May 14 '19 at 08:28

score 42 · Accepted Answer · answered May 14 '19 at 08:27

42

To get a type that is a union keys of a variable you need to use keyof typeof variableName.

const MY_OBJECT = {
    'key': 'key val',
    'anotherKey': 'anotherKey val',
};
type MY_OBJECT_KEYS = keyof typeof MY_OBJECT // "key" | "anotherKey"

answered May 14 '19 at 08:27

1 Answers1