React to things happening: the project starting, key presses, clicks, timers, and messages between sprites.
// Run code when the green flag is clicked
self.whenFlag(() => {});
// Run code once the sprite has loaded
self.whenLoaded(() => {});
// Run code when the timer passes a number of seconds
self.whenTimerElapsed(1, () => {});
// Run code when the backdrop switches to a specific one
self.whenBackdropChangesTo("Stage", () => {});
// Run code when a key is pressed
self.whenKeyPressed("any", () => {});
// Run code on a mouse event such as a click
self.whenMouse("clicked", () => {});
// Run code when a broadcast message is received
self.whenReceiveMessage("message", () => {});
// Broadcast a message to all sprites without waiting
self.broadcastMessage("message");
// Broadcast a message and wait until all receivers finish
self.broadcastMessageWait("message");