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invert ​

Problem ​

You need a reverse lookup map — swapping keys and values of an object so you can look up a key by its value.

Solution ​

Use invert(obj) to swap keys and values. Values become keys and keys become values.

ts
import { invert } from '@vielzeug/arsenal';

const roles = { 1: 'admin', 2: 'user', 3: 'guest' };
invert(roles);
// { admin: '1', user: '2', guest: '3' }

Pitfalls ​

  • If multiple keys share the same value, only one is kept — last wins.
  • All resulting keys are strings (values are coerced).