Items added to the array after the start of the map method will not be visited by the callback function. The range of elements processed by the map method is set before the first call to the callback function. The map method does not modify the array for which it was called (although the function⚙️ can do that!). Ultimately, the value of this as seen from the callback function is determined according to the usual rules for defining this as seen from a function. Otherwise, the this value will be undefined. If the thisArg parameter was passed to the map method, it will be used as the this value when callback is called.
The function⚙️ callback is called with three arguments: It is not called for missing array elements (that is, for indices that were never specified, deleted, or never assigned a value). The callback function is called only for array indices that have assigned values, including undefined. The map method calls the passed callback function once for each element, in the order of their occurrence, and constructs a new array from the results of its call.
