Wartość domyślna typuercript null lub niezdefiniowana
The value undefined means value is not assigned
& you don’t know its value.
It is an unintentional absence of value.
It means that a variable has been declared but has not yet
been assigned a value.
The value null indicates that you know that the field does not
have a value. It is an intentional absence of value.
Clever Cowfish