Scripter Javascript Tutorial

11 Variables

MDN: Grammar and types: Declarations

A variable is a kind of named storage for any kind of data.

12 var and let

MDN:

• Statements: var

• Statements: let

Variables are typically declared with the var keyword to make clear something is a new variable.

var tonic = 60;
var controlName = "Tonic";

In the above example:

1. Line 1 shows a variable tonic is declared and is assigned with the = sign the value of 60.

2. Line 2 is very similar: a variable named controlName is declared and assigned the value of “Tonic”.

Modern JavaScript also uses the let keyword, which Scripter supports. The below example has the exact outcome as using var.

let tonic = 60;
let controlName = "Tonic";

In both cases of var and let, variables can be assigned new values by leaving off the var and let keywords:

var tonic = 60;
let controlName = "Tonic";
tonic = 72;
controlName = "Range";

All of the examples in this book will use var to declare variables.