// Declare a global variable
var myOuterNumber = 1;

// Function scope
function myFunc() {
    myOuterNumber = 1; 		// Alter the global variable
    var myInnerNumber = 10;	// Declare a new variable (scoped to this function)

    console.log(myOuterNumber); // 1
    console.log(myInnerNumber); // 10
}

// Invoke the function
myFunc();

// Adjust the global variable
myOuterNumber = 2;

// View the results
console.log(myOuterNumber); // 2
console.log(myInnerNumber); // ReferenceError: myInnerNumber is not defined