Variables

Declare a variable

To declare a variable, we use a keyword var.

var num

This will create a variable named num and its value is null.

To assign initial value, just do:

var num = 10

Then, the value of num is 10.

Multiple variables

To declare multiple variables at once in var declaration, just add a comma after the first variable.

var a = 10, b = 20

It looks pretier:

var x = 5,
    y = 9,
    z = 7

Naming

Name rules:

• Contain only a-z A-Z 0-9 $ _

• Do not start with digits

• Do not match the keywords

• Variable names is sensitive case

There is no rule about naming convention, but we suggest using both camel case and snake case.

var my_var     // snake case
var yourVar    // camel case

Notes

You cannot use the variable in its declaration.

var a = a + 10
//      ^-- Cannot use variable in its own initializer.

A variable cannot be declared more than one in a scope.

var a, b
var a
//  ^-- This variable has already been declared.

All undefined variables will give an error.

puts a
//   ^-- Undefined variable.

There is no global variable, see the global module to store data globally.