Can we deduce the value of a Record datatype in TypeScript?

Is it possible to have TypeScript infer the type of statusColor as yellow instead of Color?

type Status = 'Invalid' | 'Progress' | 'Complete' | 'Error';

type Color=  'yellow' | 'red' | 'green' | 'blue';

const STATUS_TO_COLOR: Record<
  Status,
  Color
> = {
  Invalid: 'yellow',
  Progress: 'blue',
  Complete: 'green',
  Error: 'red',
} as const;

const statusColor = STATUS_TO_COLOR["Invalid"];
     //   ^ inferred as Color, can it be infered as "yellow"?

Playground link to the code

I have experimented with different approaches but none seem to work.

typescript

Answer №1

The best approach is to follow the second method you attempted

You can evaluate it for <Status, Color> compatibility

const STATUS_TO_COLOR = {
  Pending: 'orange',
  In Progress: 'blue',
  Finished: 'green',
  Issue: 'red',
} fulfills Record<Status, Color>;

(ts4.9+)

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