function-scope.js

a = { note: "I'm global" };

function foo(b) {
    // b is scoped to this function, but currently points to the same object as a
    b === a; // => true
    
    b = { note: "I'm not global" };
    // now b points to a new object
    b !== a; // => true
}

foo(a);

// a is global, b isn't.