Nearby lessons
18 of 21🎉 Node.js – Events Module
📌 What is Events Module?
What is the Events Module?
The events module in Node.js allows us to work with events. An event is an action that occurs in our application that we can respond to. Node.js is perfect for event-driven applications.
Using the events module, we can create custom events and respond to them in a non-blocking manner.
📌 Examples of Events
- On Click
- On Double Click
- On Mouse Over
- On Mouse Out
- On Submit
- On Change
- On Reset
- Key Press
🔹 Example 1: Basic Event Handling – Separate Handler Function
Node.js Environment
RUNTIME ACTIVE
const events = require('events'); const eventEmitter = new events.EventEmitter(); // Event handler function const myEventHandler = () => { console.log("Order Received! Baking a Pasta."); }; // Assign handler to the event eventEmitter.on('order-pasta', myEventHandler); // Trigger the event eventEmitter.emit('order-pasta');
Terminal Output
🔹 Example 1: Basic Event Handling – Inline Function
Node.js Environment
RUNTIME ACTIVE
const events = require('events'); const eventEmitter = new events.EventEmitter(); // Directly assign event handler inline eventEmitter.on('order-pasta', () => { console.log("Order Received! Baking a Pasta."); }); // Trigger the event eventEmitter.emit('order-pasta');
Terminal Output
🔹 Example 2: Passing Parameters in EventEmitter
Node.js Environment
RUNTIME ACTIVE
const events = require('events'); const eventEmitter = new events.EventEmitter(); // Event with parameters eventEmitter.on('order-pasta', (size, topping) => { console.log(`Order Received! Baking a ${size} Pasta with ${topping}.`); }); // Trigger event with parameters eventEmitter.emit('order-pasta', 'large', 'Black Olives');
Terminal Output
🔹 Example 3: Multiple Event Handlers
Node.js Environment
RUNTIME ACTIVE
const events = require('events'); const eventEmitter = new events.EventEmitter(); // First event handler eventEmitter.on('order-pasta', (size, topping) => { console.log(`Order Received! Baking a ${size} Pasta with ${topping}.`); }); // Second event handler eventEmitter.on('order-pasta', (size) => { if (size === 'large') { console.log("Serving Complimentary Red Bull.."); } }); // Trigger the event eventEmitter.emit('order-pasta', 'large', 'Black Olives');
Terminal Output
🧠 Test Your Knowledge
4 QuestionsProgress: 0 / 4
Keep Going!Thread Pool in Node.js