Handlers

Handlers are methods on Workers that can receive and process external inputs, and can be invoked from outside your Worker. For example, the fetch() handler receives an HTTP request, and can return a response:

export default {
  async fetch(request, env, ctx) {
    return new Response('Hello World!');
  },
};

The following handlers are available within Workers:

• Alarm Handler
• Email Handler
• Fetch Handler
• Queue Handler
• Scheduled Handler
• Tail Handler

Handlers in Python Workers

When you write Workers in Python, handlers are prefixed with on_. For example, on_fetch or on_scheduled.