Signal

Signals are what Phaser uses to handle events and event dispatching.
You can listen for a Signal by binding a callback / function to it.
This is done by using either Signal.add or Signal.addOnce.

For example you can listen for a touch or click event from the Input Manager
by using its onDown Signal:

game.input.onDown.add(function() { ... });

Rather than inline your function, you can pass a reference:

game.input.onDown.add(clicked, this);
function clicked () { ... }

In this case the second argument (this) is the context in which your function should be called.

Now every time the InputManager dispatches the onDown signal (or event), your function
will be