From MDN:
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.
If you expect this to be the array, you have to call arr.forEach(function(e){}, arr); using the optional second paramater, thisArg.
