Package Exports

bufout
bufout/dist/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (bufout) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

bufout

Spawn child processes with prefixed buffered output.

Features

Output modes:
- "inherit" (default) pipe through the child process's stdout and stderr to the host process.
- "buffered" buffers of stdout and stderr in a common buffer to preserve ordering between the two and the buffer is flushable upon failure.
Output prefix: Adds a prefix to every line the child writes to stdout or stderr.
Returns a Promise allowing the child process to be awaited.
Forwards exits and SIGINT (interrupts triggered by Ctrl + C in terminals) to the child process.
No dependencies, except for Node.js APIs.

Usage

npm install --save bufout

import { spawn, SpawnFailure } from "bufout";

await spawn(
  // Provide the command
  "some-command",
  // Arguments for the command is passed through an array
  ["--fail"],
  // Additional options
  {
    // Adds a prefix to any line printed to stdout or stderr
    outputPrefix: "[child] ",
    
    // Buffers the stdout and stderr of the process
    // Alternatively, "inherit" can be passed to bypass buffering and write directly to stdout and stderr
    // while still applying any prefix.
    outputMode: "buffered",

      // Optionally pass the stdout and stderr streams used when flushing the buffer
    // stdout: process.stdout,
    // stderr: process.stderr,

    // Forwards extra options to the underlying call to node:child_process's spawn
    // shell: true,
    // timeout: 1000,
  },
).catch((error) => {
  // A special error is thrown upon failures
  if (error instanceof SpawnFailure) {
    // Yields: Running 'some-command' failed (code = 1)
    console.error(error.message);
    // Flush the buffered output, preserving order across the streams,
    // to correctly interleave information with errors as they were emitted by the child process.
    // Takes an optional argument of the stream to flush (default is "both" stdout and stderr).
    error.flushOutput("stderr");
  } else {
    throw error;
  }
});

// To manually kill the child process, call `kill` on the object returned from `spawn`:
const sleeper = spawn("sleep", ["10"]);
// If you get impatient
sleeper.kill();