On Start

An event that runs when the program starts.

The on start is a special event that runs when the program starts, before any other event. Use this event to initialize your program.

In this example, on start sets a dimmer brightness on the screen and the button handler shows a string.

input.onButtonPressed(Button.A, () => {
    basic.showString("Hello!")
})
led.setBrightness(50)

What about JavaScript?

on-start only exists in the block editor. In JavaScript, all code executes sequentially from the first line.

Hey, my events moved!

When we transform the blocks into JavaScript, we always place all the event registrations (buttons, shake, …) before launching the on start code.

If a block from on start pauses, other registered events will have the opportunity to run as well.