/dx-audit

Respect Pipes and the TTY

A well-behaved CLI checks whether it talks to a terminal or a pipe. Disable color and spinners when stdout is not a TTY, when NO_COLOR is set, when TERM=dumb, or on --no-color; offer --json for machine-readable output; write progress and logs to stderr so they never corrupt piped stdout; and read stdin when no file argument is given. Otherwise ANSI codes and spinner frames land in the file the user redirected to. Note that process.stdout.isTTY is undefined under a pipe, not false, so test for truthiness.

Incorrect (color and progress always on, mixed into stdout):

console.log(chalk.green("done"));        // ANSI codes land in piped output
console.log(`Processing ${file}...`);    // progress pollutes stdout
// no --json, no stdin support

Correct (TTY-aware, machine output on request, progress to stderr):

const useColor =
  Boolean(process.stdout.isTTY) && !process.env.NO_COLOR && process.env.TERM !== "dumb" && !flags.noColor;
if (flags.json) {
  process.stdout.write(JSON.stringify(result)); // clean, parseable
} else {
  console.error(`Processing ${file}...`);        // progress to stderr
  console.log(useColor ? chalk.green("done") : "done");
}
const input = file ? readFile(file) : readStdin(); // read stdin when no file