Understanding this

this is decided by how a function is called. Called as obj.method(), this is obj. Pull the method out and call it on its own, and this is lost. Arrow functions do not have their own this; they use the this of the code around them, which makes them ideal for callbacks inside methods. fn.bind(obj) returns a copy of a function with this locked to obj.

How it reads

• ship.greet() is called on ship, so this is ship
• The arrow callback in countdown borrows this from the method
• bind makes a new function whose this is fixed

Cloud tip: Inside a method, use an arrow function for any callback that needs this.