Type-safe way to transform a key and a value into an object with that single key/value

Question

I want to write a function valueToObject that, given a key and a value, yields an object with that single key and value, e.g.:

valueToObject(\'myKe         


        

Answer 1

When using a computed property the type with a generic parameter the type will be inferred to { [name: string]: V }. This seems to be related to this issue, which although is marked as fixed, you can see @jcalz commented about 4 days ago that this is still happening on 2.9.

Edit This issue seems to be a close match and is still open with a target of 3.0 so we may get a fix soon

The only work around is to use a type assertion:

function valueToObject<K extends string, V>(key: K, value: V): Wrapped<K, V> {
    return { [key]: value } as Wrapped<K, V>;
}
//OR
function valueToObject<K extends string, V>(key: K, value: V): Wrapped<K, V> {
    var result = {} as   Wrapped<K, V>
    result[key] = value;
    return result;
}

I suggest you report this on GitHub, or comment on the issue to draw attention to the fact that this still happens.