Map.prototype.forEach() | javascript foreach object
TheforEachmethodexecutestheprovidedcallbackonceforeachkeyofthemapwhichactuallyexist.Itisnotinvokedforkeyswhichhavebeendeleted.However,itisexecutedforvalueswhicharepresentbuthavethevalueundefined.callbackisinvokedwiththreearguments:theentrysvaluetheentryskeytheMapobjectbeingtraversedIfathisArgparameterisprovidedtoforEach,itwillbepassedtocallbackwheninvoked,foruseasitsthisvalue.Otherwise,thevalueundefinedwillbepassedforuseasitsthisvalue.Thethisvalueultimatelyobservablebycallbackisdeterminedacc...
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.
callback is invoked with three arguments:
the entrys value the entrys key the Map object being traversedIf 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[1].
Each value is visited once, except in the case when it was deleted and re-added before forEach has finished. callback is not invoked for values deleted before being visited. New values added before forEach has finished will be visited.
References the usual rules fo...