Map.forEach method has parameters in the order of value, key, map.
Hence for a {key, value} pair:

var m = new Map()
m.set('a', 1)
m.set('b', 2)
m.forEach((v, k, m) => console.log(`key:${k} value:${v} map:${m}`))// key:a value:1 map:[object Map]
// key:b value:1 map:[object Map]