Interactive Development (REPL & Notebook)

After your program runs on the device, you can send more BlueScript code without editing files and running bscript project run again.

Try the Notebook

This walkthrough continues from Blink LED (GPIO package installed, LED wired).

1. Shorten index.bs

Keep the entry file small so the Notebook opens quickly. Setup belongs here; experiments go in cells.

src/index.bs

import { GPIO, PinMode, PinLevel } from "gpio";

// CHANGE 2 TO 23 IF USING AN EXTERNAL LED
const led = new GPIO(2, PinMode.InputOutput);

console.log("LED ready.");

The led variable stays available in later cells.

2. Start the Notebook

bscript project run --with-notebook

The CLI runs index.bs, then opens the Notebook in your browser (http://localhost:3000). Leave the terminal open until you are done.

3. Run cells

1. Type code in the bottom cell.
2. Press Shift+Enter (or the play button).
3. See console.log output on the right.

Example—run these as two separate cells:

console.log("LED on");
led.write(PinLevel.High);

console.log("LED off");
led.write(PinLevel.Low);

Press Ctrl+D in the terminal to exit.

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Other modes

Project REPL

bscript project run --with-repl

After index.bs runs, type one line at the > prompt. Installed packages (e.g. gpio) can be imported here. Exit with Ctrl+D.

Global REPL

bscript repl -b esp32
# or, without hardware:
bscript repl -b host

Use this for quick syntax checks without a project. GPIO and other installed libraries are not available. Exit with Ctrl+D.

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Good to know

• Device name: Notebook and Project REPL connect using deviceName in bsconfig.json. Global REPL uses the -d flag instead. The name must match what was set during bscript board flash-runtime. See bsconfig.json.
• Code on the device is lost after a reboot—run the command again to re-upload.