プログレス表示

progress.js

const readline = require('readline');

console.log('start');

Array.from(Array(100), (_, i) => i + 1).forEach(i => {
	setTimeout(() => {
		/*
		// ※ メッセージの長さが減少する場合は使えない
		process.stdout.write(`working... ${i}%\r`);
		/*/
		// child_process でも正常に動作させるには readlineを使う
		readline.clearLine(process.stdout);
		readline.cursorTo(process.stdout, 0);
		process.stdout.write(`working... ${i}%`);
		//*/
	}, i * 30);
});

spawn.js

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

const useCmd = false;

const progress =
	useCmd
		? spawn("cmd.exe", [
			"/c",
			"progress-bat.bat",
		])
		: spawn('node', [
			'progress.js',
		]);

//*
progress.stdout.pipe(process.stdout);
progress.stderr.pipe(process.stderr);
/*/
progress.stdout.setEncoding('utf8');
progress.stdout.on('data', (data) => {
	process.stdout.write(data);
});

progress.stderr.on('data', (data) => {
	console.log(`stderr: ${data}`);
});
//*/

progress.on('close', (code) => {
	console.log(`\nchild process exited with code ${code}`);
});