A variable is a "container" for data, that can change (which is why it's "variable", get it?). Variables are declared by giving them a variable name, as well as value (or "content" or "data"). There are 3 ways to declare a variable:
// the "var" keyword is not really used anymore, but you'll still see it in older// code. It's suggested not to use it anymore. Use let instead!var myVariableName = "This is a string value";// The "let" keyword defines a variable where the value and type can be changed later.let myOtherVariable = "We can change this later";// If you're going to define the actual value later, you can simply declare it// without giving it a valuelet changeMeLater;// We can change the content of an existing variable by omitting the "let" keyword.changeMeLater = "Oh cool I have a value now!"// The "const" keyword defines a variable that can't change type but, in the case// of objects and arrays (see "Data Types" below) can be modified. You'll see this// better in context later on.const notReallyConstant = "I cannot be modified";noTreallyConstant = "This will fail";
Let's break down a single line here to look at the syntax:
The variable name also called identifier is created. There are some limitations to identifier names, see this page for more details.
= is an operator that means "insert whatever comes after me, into the variable before me"