25 lines
739 B
JavaScript
25 lines
739 B
JavaScript
type Key1 = 'foo' | 'bar'; // make an enum type with known key set
|
|
var o1: {[key: Key1]: number} = {
|
|
foo: 0,
|
|
bar: "", // error: string ~/~ number
|
|
};
|
|
o1.foo; // OK
|
|
o1.qux; // error: qux not found
|
|
o1.toString(); // ok
|
|
|
|
type R = {foo: any, bar: any};
|
|
type Key2 = $Keys<R>; // another way to make an enum type, with unknown key set
|
|
var o2: {[key: Key2]: number} = { foo: 0 }; // OK to leave out bar
|
|
o2.bar; // OK to access bar
|
|
o2.qux; // error: qux not found
|
|
|
|
class C<X> {
|
|
x: $Subtype<{[key: $Keys<X>]: any}>; // object with larger key set than X's
|
|
}
|
|
class D extends C<{foo: number, bar: string}> {
|
|
x: { foo: number, qux: boolean }; // error: qux not found
|
|
}
|
|
|
|
type AnyKey = $Keys<Object>;
|
|
var o3: {[key: AnyKey]: number} = { foo: 0 };
|