Multi Arg

Node's multi-argument events: an event whose payload type is a tuple `[A, B, …]` emits and listens with one argument per element — exactly like real Node's `emit('data', chunk, size)` / `on('data', (chunk, size) => …)`. This file runs the same way under Node.js.

import { EventEmitter } from 'events';

class Download extends EventEmitter<{
  progress: [number, number];
  done: [string];
  error: [];
}> {
  run(): void {
    this.emit("progress", 512, 1024);
    this.emit("progress", 1024, 1024);
    this.emit("done", "/tmp/file.bin");
  }
}

const d = new Download();
d.on("progress", (loaded: number, total: number) => {
  console.log("progress: " + loaded + "/" + total);
});
d.on("done", (path: string) => {
  console.log("saved to " + path);
});
d.run();

View source on GitHubexamples/eventemitter/multi_arg.ts

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