drain

Pull all data from Deno.Readers and pass it to a simple ondata listener.

Kinda like readableStream.on("data", listener) in node.

Usage

Call drain on a Deno.Reader to start pulling data. The ondata handler will be called with every chunk read from the reader.

import { drain } from "https://denopkg.com/chiefbiiko/drain/mod.ts";

function ondata(chunk: Uint8Array): void {/* handle data */}
function onerror(err: Error): void {/* handle error */}
function onclose(): void {/* handle close */}

// conn is a Deno.Reader - lets pretend top-level await landed
const conn: Deno.Conn = await Deno.dial("tcp", "419.0.0.1:41900");

// drain pulls forever/all data from the reader
const cancel = drain(conn, ondata, onerror, onclose);

// go about your business with all those handlers setup
// ..hack .. hack .. hack.. hack... (maybe call cancel)..... hack hack...

API

`cancel = drain(reader, ondata[, onerror][, onclose][, options])`

Pull all data from the reader and pass it to a simple ondata handler.

export function drain(
  reader: Deno.Reader,
  ondata: (chunk: Uint8Array) => any,
  onerror: (err: Error) => any = (err: Error): void => {
    throw err;
  },
  onclose: () => any = (): void => undefined,
  { limit = Infinity }: DrainOptions = {}
): Cancel

The returned cancel(err?: Error): void function allows to stop reading. Once invoked any pending reads are awaited before invoking either the onerror or onclose handler. If cancel is invoked with an error the onerror handler is called with that error, otherwise the onclose handler gets invoked as reaction to the cancelation. Canceling is a bike-shed feature, fx if reader never resolves its read promises, the cancelation will never take place because we are blocking while awaiting the read promise.

The option's limit property can be used to cap the number of reads and likewise the number of the ondata handler invocations.

`interface DrainOptions`

export interface DrainOptions {
  // max number of reads
  limit?: number;
}

`type Cancel`

export type Cancel = (err?: Error) => void;

License

MIT

chiefbiiko / drain