Running a command in JavaScript

execFile with an argument array, promisified and awaited.

import { execFile } from "node:child_process";
import { promisify } from "node:util";

const run = promisify(execFile);

const { stdout } = await run(process.execPath, ["-e", "console.log(21 * 2)"]);
console.log(stdout.trim());

try {
  await run(process.execPath, ["-e", "process.exit(3)"]);
} catch (error) {
  console.log("exit code:", error.code);
}

How it works

1. Pass arguments as an array: no shell, no quoting bugs.
2. The promise rejects on a non-zero exit, carrying stderr.
3. spawn is the streaming alternative for large output.

Keywords and builtins used here

• await
• catch
• const
• from
• import
• try

The run, in numbers

Lines

13

Characters to type

349

Tokens

86

Three-star pace

110 tpm

At the three-star pace of 110 tokens a minute, this run takes about 47 seconds.

Type this snippet

Step 2 of 3 in Crypto & processes, step 16 of 18 in Node.js.

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