Map.prototype.forEach()

The forEach() method of Map instances executes a provided function once per each key/value pair in this map, in insertion order.

The forEach method executes the provided callback once for each key of the map which actually exist. It is not invoked for keys which have been deleted. However, it is executed for values which are present but have the value undefined.

the entry’s value the entry’s key the Map object being traversed

If a thisArg parameter is provided to forEach, it will be passed to callback when invoked, for use as its this value. Otherwise, the value undefined will be passed for use as its this value. The this value ultimately observable by callback is determined according to the usual rules for determining the this seen by a function.

Syntax example: forEach(callbackFn)