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Event-Driven Programming

Event-driven programming is a paradigm where program flow is determined by events such as user actions, sensor outputs, or messages from other programs.

Core Concepts​

Example: JavaScript​

// Event listener
document.getElementById('button').addEventListener('click', (event) => {
    console.log('Button clicked!');
    event.target.style.background = 'blue';
});

// Custom events
class EventEmitter {
    constructor() {
        this.events = {};
    }

    on(event, callback) {
        if (!this.events[event]) {
            this.events[event] = [];
        }
        this.events[event].push(callback);
    }

    emit(event, data) {
        if (this.events[event]) {
            this.events[event].forEach(callback => callback(data));
        }
    }
}

// Usage
const emitter = new EventEmitter();
emitter.on('data', (data) => console.log('Received:', data));
emitter.emit('data', { message: 'Hello!' });

Advantages​

✅ Responsive applications
✅ Loose coupling
✅ Asynchronous handling
✅ Scalable architecture

Use Cases​

  • GUI applications
  • Web applications
  • Real-time systems
  • IoT devices

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