10 2 using functions

1/*A function call is the act of using a function by referring to its 
2name, followed by parentheses. A synonymous term is function 
3invocation, and we will sometimes say that we are "invoking a 
4function."
5
6Within parentheses, a comma-separated list of arguments may be 
7provided when calling a function. These are sometimes called inputs, 
8and we say that the inputs are "passed to" the function.*/
9
10//A generic function call looks like this:
11functionName(argument1, argument2,...,argumentN);
12
13/*Every function provides a return value, which can be used by the 
14calling program---for example, to store in a variable or print to 
15the console.*/
16
17//Example
18//A return value may be stored in a variable.
19
20let stringVal = String(42);
21/*It may also be used in other ways. For example, here we use the 
22return value as the input argument to console.log without storing it.*/
23
24console.log(String(42));
25
2642

1/*If a function doesn't provide an explicit return value, the special 
2value undefined will be returned.*/
3
4//Example
5let returnVal = console.log("LaunchCode");
6console.log(returnVal);
7
8//LaunchCode
9//undefined
10