Variables and Symbols

Variables can be declared using the following syntax:

type name

E.x.

let x

OR

const x

Declared variables will have space reserved for them but will start with an undefined value.

Variables can be assigned values using the following syntax:

name = value

E.x.

x = 5

Variables can be defined (declared and assigned) using the following syntax:

type name = value

E.x.

let x = 5

OR

const x = 5

Defining a variable is equivalent to declaring it and then assigning it a value.

Global Variables

Global variables (variables declared outside of a function) can only be defined with constant expressions, which include expressions that can be evaluated numerically at compile time (such as 1+2*3, which will be replaced by the constant 7), string literals, like "Hello, World!", and function definitions. Global variables may be assigned different values inside of functions. Global variables can be exported.

Local Variables

Local variables (variables defined inside a function), on the other hand, can be defined with any value and can be reassigned any value. However, they can only be accessed within the function (scope) that they are declared in*, and cannot be exported.