Invert a Map object

Question

I was wondering, what is the most convenient way to invert keys and values in a Map. Is there any builtin method or should it be done by iterating over keys and values?

const map: Map<string, number> = new Map()

const inverse: Map<number, string>

Answer 1

You could pass the inverse tuples to the constructor, using Array.from and Array#reverse:

new Map(Array.from(origMap, a => a.reverse()))

See it run on an example:

const origMap = new Map([[1, "a"],[2, "b"]]);
console.log(...origMap);

// Reverse:
const inv = new Map(Array.from(origMap, a => a.reverse()));
console.log(...inv);