In this guide, we'll create a simple script that outputs ordinal numbers with a delay and learn how to run it on Flipper Zero in different ways. All you need is your Flipper Zero, a PC, and a USB cable.

Step 1. Create the script file

Create a new text file first_app.js. Paste the code below into it and save the file:

print("start");
delay(1000);
print("1");
delay(500);
print("2");
delay(500);
print("3");
delay(500);
print("end");

What the code does:

Outputs the text start, waits 1 second
Outputs the numbers 1, 2 and 3, with a 0.5-second pause after each number
Outputs the text end

The print() function is used to output text. The string to be output is in the brackets. This is a built-in function, so you don't need to include additional JS modules. You can use this function anywhere in your application.

Another built-in function, delay(), implements delay. The delay time in milliseconds is given in the brackets. Since 1000 milliseconds equals 1 second, a 1-second delay is written as 1000, and a 0.5-second delay as 500.

Note: Find the list of built-in functions in Built-in functions.

Step 2. Copy the file to Flipper Zero

To copy the JavaScript file to Flipper Zero, follow these steps:

Connect your Flipper Zero to your PC via USB.
Open the qFlipper application.
Go to the File manager tab and open the path SD Card/apps/Scripts/.
Drag and drop the file into the qFlipper window.

Note: To learn more about qFlipper, visit the dedicated section in our user documentation.

Your script is now ready to run on Flipper Zero.

Step 3. Run your script

You can launch your app in two ways:

From the Flipper Zero menu
Remotely from your PC using the CLI (command-line interface)

Let's explore them both.

How to run a script from Flipper Zero's menu

Go to Apps → Scripts in your Flipper Zero's menu. Here, you'll see a list of scripts located in the SD Card/apps/Scripts/ folder.
Select the script you want to run.
Press the OK button to run the script.

The Flipper Zero screen will display the strings with the specified delay, as defined by the print() and delay() functions.

How to run script using CLI

The command-line interface (CLI) is a text-based interface that lets you control your Flipper Zero from your computer, including running scripts. Running JavaScript apps via CLI is useful for debugging, as it lets you write and test code remotely, without switching between your PC and the device.

To run the script via CLI:

Connect your Flipper Zero to your PC via USB.
Access the CLI using one of the recommended methods.
Enter the js path command, replacing path with the path to the script file on your Flipper Zero:

js /ext/apps/Scripts/first_app.js

As you can see, unlike running JavaScript apps from the Flipper Zero UI, all output from the print() function is sent to the CLI, not the device screen.

Next step: Developing apps using JavaScript SDK