Execute same command on multiple directories

each-dir.js

#! node

// example:
//   each-dir dir1 somewhere/dir2 -- npm ci

const { spawn } = require("child_process");

(async () => {
  const args = process.argv.slice(2);
  const i = args.indexOf("--");
  if (i === -1) throw new Error("specify command after --");
  const dirs = args.slice(0, i);
  const command = args.slice(i + 1);

  for (const dir of dirs) {
    await new Promise((resolve, reject) => {
      const [commandName, ...commandArgs] = command;
      spawn(commandName, commandArgs, {
        cwd: dir,
        stdio: ["inherit", "inherit", "inherit"]
      }).on("close", (code) => {
        if (code === 0) {
          resolve();
        } else {
          reject();
        }
      });
    });
  }
})();