It is possible to define a variable using
var something;, without
giving it a value. What happens when you take the value of such a variable?
In terms of tentacles, this variable ends in thin air—it has nothing to grasp. When
you ask for the value of an empty place, you get a special value named
undefined. Functions that do not return a specific value but are called for
their side effects, such as
There is also a similar value,
null, whose meaning is “this value ...