main.js

#!/usr/bin/env node
'use strict';

const https = require('https');
const semver = require('semver');

const readUtf8 = stream =>
	new Promise((resolve, reject) => {
		const parts = [];

		stream.on('error', reject);

		stream.on('data', part => {
			parts.push(part);
		});

		stream.on('end', () => {
			resolve(Buffer.concat(parts).toString('utf8'));
		});
	});

const username = process.argv[2];

if (!username) {
	console.error('Usage: sub-1.0 <username>');
	process.exit(1);
	return;
}

const request = https.get('https://registry.npmjs.com/-/v1/search?size=250&text=maintainer:' + encodeURIComponent(username));

request.on('response', async response => {
	const json = await readUtf8(response);
	const data = JSON.parse(json);
	const packages = data.objects.map(object => object.package);
	const unstable = packages.filter(package_ => semver.lt(package_.version, '1.0.0'));
	const unstableNames = unstable.map(package_ => package_.name);

	console.log(unstableNames.sort().join('\n'));
});

package.json

{
	"name": "sub-1.0",
	"bin": "main.js",
	"dependencies": {
		"semver": "5.3.0"
	}
}