Cliffy ❯ Keypress

Keypress module with promise, async iterator and event target API

❯ Content

• Install
• Usage
  • Promise
  • Async Iterator
  • Event Target
• API
  • keypress
  • Keypress
  • KeyPressEvent
• Contributing
• License

❯ Install

This module can be imported directly from the repo and from following registries.

Deno Registry

import {
  Keypress,
  keypress,
  KeyPressEvent,
} from "https://deno.land/x/cliffy@<version>/keypress/mod.ts";

Nest Registry

import {
  Keypress,
  keypress,
  KeyPressEvent,
} from "https://x.nest.land/cliffy@<version>/keypress/mod.ts";

Github

import {
  Keypress,
  keypress,
  KeyPressEvent,
} from "https://raw.githubusercontent.com/c4spar/deno-cliffy/<version>/keypress/mod.ts";

❯ Usage

There are two ways to use this module. You can use the keypress() method, which returns a global instance of the KeyPress class, or you can create a new instance of the KeyPress class. There is no difference between these two ways, except that the keypress() method always returns the same instance, unless the .dispose() method is called. In this case a new instance is returned.

Promise

The keypress module can be used as promise. It reads one chunk from stdin and returns an KeyPressEvent for the first parsed character.

import {
  keypress,
  KeyPressEvent,
} from "https://deno.land/x/cliffy/keypress/mod.ts";

const event: KeyPressEvent = await keypress();

console.log(
  "type: %s, key: %s, ctrl: %s, meta: %s, shift: %s, alt: %s, repeat: %s",
  event.type,
  event.key,
  event.ctrlKey,
  event.metaKey,
  event.shiftKey,
  event.altKey,
  event.repeat,
);

$ deno run --unstable --reload https://deno.land/x/cliffy/examples/keypress/promise.ts

Async Iterator

The keypress module can be used as async iterator to iterate over all keypress events. The async iterator reads chunk by chunk from stdin. On each step, it reads one chunk from stdin and emits for each character a keypress event. It pauses reading from stdin before emitting the events, so stdin is not blocked inside the for loop.

import { Keypress, keypress } from "https://deno.land/x/cliffy/keypress/mod.ts";

for await (const event: KeyPressEvent of keypress()) {
  console.log(
    "type: %s, key: %s, ctrl: %s, meta: %s, shift: %s, alt: %s, repeat: %s",
    event.type,
    event.key,
    event.ctrlKey,
    event.metaKey,
    event.shiftKey,
    event.altKey,
    event.repeat,
  );
  if (event.ctrlKey && event.key === "c") {
    console.log("exit");
    break;
  }
}

$ deno run --unstable --reload https://deno.land/x/cliffy/examples/keypress/async_iterator.ts

Event Target

The Keypress class extends from the EventTarget class that provides a .addEventListener() method that can be used to register event listeners. The addEventListener method starts an event loop in the background that reads from stdin and emits an event for each input. During this time stdin is blocked for other resources. The event loop can be stopped with keypress().dispose(). The promise and async iterator based solution does not start an event loop in the background.

import {
  keypress,
  KeyPressEvent,
} from "https://deno.land/x/cliffy/keypress/mod.ts";

keypress().addEventListener("keydown", (event: KeyPressEvent) => {
  console.log(
    "type: %s, key: %s, ctrl: %s, meta: %s, shift: %s, alt: %s, repeat: %s",
    event.type,
    event.key,
    event.ctrlKey,
    event.metaKey,
    event.shiftKey,
    event.altKey,
    event.repeat,
  );
  if (event.ctrlKey && event.key === "c") {
    console.log("exit");
    keypress().dispose();
  }
});

$ deno run --unstable --reload https://deno.land/x/cliffy/examples/keypress/event_target.ts

❯ API

keypress

• keypress(): Keypress

Keypress

• new Keypress(): Promise<KeyPressEvent> | AsyncIterator<KeyPressEvent> | EventTarget

KeyPressEvent

• key?: string
• sequence?: string
• code?: string
• ctrlKey: boolean
• metaKey: boolean
• shiftKey: boolean
• altKey: boolean
• repeat: boolean

❯ Contributing

Any kind of contribution is welcome! Please take a look at the contributing guidelines.

❯ License

MIT