Using JavaScript with NodeMCU: A Comprehensive Guide

Introduction

NodeMCU is a popular development board based on the ESP8266 microcontroller, widely used for IoT applications due to its low cost and built-in Wi-Fi capability. Traditionally, NodeMCU firmware supports the Lua scripting language, and most developers use C++ via the Arduino IDE. However, JavaScript can also be used on NodeMCU through platforms such as Espruino and Mongoose OS.

This article explores how to use JavaScript on NodeMCU, covering different firmware options, installation procedures, and example projects.

Why Use JavaScript on NodeMCU?

JavaScript is a widely used language for web development, and bringing it to microcontrollers can simplify development, especially for web-based IoT applications. Benefits include:

• Faster development: JavaScript is easier to write and debug compared to low-level languages like C.
• Event-driven programming: JavaScript’s asynchronous nature is well-suited for IoT applications.
• Integration with web technologies: Easy communication with web servers and front-end applications.

However, JavaScript on microcontrollers has limitations such as increased memory consumption and reduced execution speed compared to C.

Methods to Use JavaScript on NodeMCU

1. Using Espruino Firmware

Espruino is a JavaScript interpreter for microcontrollers that enables scripting directly on the device.

Steps to Install Espruino on NodeMCU

1. Download the Espruino firmware:
   • Visit Espruino’s website and download the ESP8266 firmware.
2. Flash the firmware:
   • Use esptool.py to flash the firmware:

     esptool.py --port /dev/ttyUSB0 write_flash -fm dio -fs 4MB 0x00000 espruino_esp8266.bin
     

3. Connect to Espruino:
   • Use the Espruino Web IDE or a serial terminal like PuTTY to interact with the board.

Writing JavaScript Code on Espruino

Once Espruino is installed, you can run JavaScript directly on the board. Example: Blinking an LED on GPIO2 (D4).

setInterval(function() {
  digitalWrite(D4, !digitalRead(D4));
}, 1000);

2. Using Mongoose OS

Mongoose OS is an IoT firmware development platform that supports JavaScript (mJS engine) and C.

Steps to Install Mongoose OS on NodeMCU

1. Download and install Mongoose OS:
   • Install Mongoose OS from mongoose-os.com.
2. Flash the firmware:
   • Connect NodeMCU to your PC and flash Mongoose OS using:

     mos flash esp8266
     

3. Write JavaScript code:
   • Open the Mongoose Web IDE and create a init.js file.

Example: Blinking an LED with Mongoose OS

load('api_gpio.js');
load('api_timer.js');

let led = 2;
GPIO.set_mode(led, GPIO.MODE_OUTPUT);

Timer.set(1000, Timer.REPEAT, function() {
  GPIO.toggle(led);
}, null);

Comparison: Espruino vs Mongoose OS

Espruino is better for beginners and quick prototyping, while Mongoose OS is better for production-ready IoT applications.

Conclusion

Using JavaScript on NodeMCU opens up new possibilities for IoT development, making it easier to integrate with web technologies. Whether you choose Espruino for simplicity or Mongoose OS for advanced features, JavaScript can help streamline development and improve productivity.

Read This: Getting Started with Espruino

Would you like to see more JavaScript projects for NodeMCU? Let us know in the comments!