JavaScript Variables Scope

In JavaScript there are two types of variables scope:

• Local scope
• Global scope

Scope determines the accessibility (visibility) of these variables.

Global variables can be accessed from any function.

The example of variable created in global scope:

 var userName = "Alice";

// code can use userName 
function myFunction1() {
    // code here can also use userName 
}
function myFunction2() {
    // code here can also use userName 
    function myFunction3() {
        // code here can also use the same userName 
    }
}

Local variables can only be accessed from the function they are declared.

// code here can NOT see userName 
function myFunction() {
    var userName = "Bob";
    // code here CAN see and use userName 
}