The var statement is used to declare a variable, and outside of
a function its use is optional. While a variable can be declared
simply by assigning it a value, it is good practice to use var
as there are two cases in functions where it is necessary:
If a global variable of the same name exists.
If recursive or multiple functions use
variables of the same name.
You can also declare more than one variable and, optionally, assign values
at the same time:
var i = 0, x, max = 57;