Quick and dirty script to verify node and npm "engine" versions defined in `package.json` (Note it ignores patch numbers)

check-engine.js

#!/usr/bin/env node

const exec = require("child_process").exec;
const pkg = require('../package.json');

// Helper script that ensures developers are using the same node versions

function runVersionCommand(command, callback) {
	exec(command, function(execError, stdin, stderr) {
		const commandDescription = JSON.stringify(command);
		if (execError) {
			const runError = new Error("Command failed: " + commandDescription);
			if (stderr) {
				runError.stderr = stderr.trim();
			}
			if (execError) {
				runError.execError = execError;
			}
			return callback(runError);
		}
		else {
			return callback(null, {
				version: stdin.toString().split('\n')[0].trim().replace(/^v/,''),
			});
		}
	});
}

function parseVersionString (str) {
	if (typeof(str) !== 'string') { return false; }
	const x = str.split('.');
	// parse from string or default to 0 if can't parse
	const maj = parseInt(x[0]) || 0;
	const min = parseInt(x[1]) || 0;
	const pat = parseInt(x[2]) || 0;
	return {
		major: maj,
		minor: min,
		patch: pat
	}
}

console.log(`👮 Checking engine versions`);

const wantedNode = parseVersionString(pkg.engines.node.replace(/^\^/,'').replace(/^v/,''));
const wantedNpm = parseVersionString(pkg.engines.npm.replace(/^\^/,'').replace(/^v/,''));

runVersionCommand('node --version', (err, response) => {
	if (err) {
		console.log(err);
		process.exit(1);
	}

	const seenNode = parseVersionString(response.version);

	if (seenNode.major !== wantedNode.major || (seenNode.major === wantedNode.major && seenNode.minor !== wantedNode.minor)) {
		console.log('\x1b[31m%s\x1b[0m', `👮 Your "node" versions is incompatible. Wanted ${pkg.engines.node}`);
		console.log('\x1b[31m%s\x1b[0m', `Try running "nvm use" (https://github.com/creationix/nvm)`);
		process.exit(1);
	}

	runVersionCommand('npm --version', (err, response) => {
		if (err) {
			console.log(err);
			process.exit(1);
		}

		const seenNpm = parseVersionString(response.version);

		if (seenNpm.major !== wantedNpm.major || (seenNpm.major === wantedNpm.major && seenNpm.minor !== wantedNpm.minor)) {
			console.log('\x1b[31m%s\x1b[0m', `👮 Your "npm" versions is incompatible. Wanted ${pkg.engines.npm}`);
			console.log('\x1b[31m%s\x1b[0m', `Try running "npm install npm@${wantedNpm.major}.${wantedNpm.minor} -g"`);
			process.exit(1);
		}

		console.log(`👮 ✅`);
	});
});