Simple settings manager for nodejs apps

example.js

const Settings = require('./Settings').shared;
// or
const Settings = require('./Settings')('~/my-app-settings.json');

const { prompt } = require('inquirer');

(async () => {
	const wait = delay => new Promise(resolve => setTimeout(() => resolve(), delay));

	try {
		const answers = await prompt([{
			name: 'firstName',
			message: 'What\'s your name?',
			prefix: 'i.',
			default: 'John',
			filter: input => input.trim(),
			validate: input => input.length > 0
		}, {
			name: 'lastName',
			message: 'And your last name?',
			prefix: 'ii.',
			default: 'Doe',
			filter: input => input.trim(),
			validate: input => input.length > 0
		}, {
			name: 'bday',
			message: 'When are you born?',
			prefix: 'iii.',
			default: new Date().toLocaleString(),
			when: a => a.firstName && a.lastName
		}]);

		const user = {};

		user.first = answers.firstName;
		user.last = answers.lastName;
		user.bday = new Date(answers.bday);
		user.age = Math.abs(new Date().getFullYear() - new Date(answers.bday).getFullYear());

		Settings.set('user', user);

		await wait(500);

		console.log({
			exists: Settings.has('user'),
			content: Settings.get('user')
		});

		await wait(500);

		Settings.delete('user');

		console.log({
			exists: Settings.has('user'),
			content: Settings.get('user')
		});
	} catch (error) {
		throw error;
	}
})();

settings.js

const { existsSync, writeFileSync, readFileSync } = require('fs');
const { join } = require('path')

class Settings {
	static shared = new Settings()

	filepath = path.join(__dirname, 'settings.json')

	constructor(filePath) {
		this.initialize()

		if (filePath) {
			this.setFilePath(filePath)
		} else {
			this.setFilePath(path.join(__dirname, 'settings.json');
		}
	 }

	setFilePath(fp) {
		this.filepath = fp
	}

	initialize() {
		if (existsSync(this.filepath) === false) {
			writeFileSync(this.filepath, JSON.stringify({}, null, 2));
		}
	}

	static has(key) {
		const settings = JSON.parse(readFileSync(this.filepath, 'utf8'));
		return settings[key] !== undefined;
	}

	static get(key) {
		const settings = JSON.parse(readFileSync(this.filepath, 'utf8'));

		if (key) return settings[key];

		return settings;
	}

	static set(key, value) {
		const settings = JSON.parse(readFileSync(this.filepath, 'utf8'));
		const data = {};

		data[key] = value;

		writeFileSync(this.getFilePath(), JSON.stringify(Object.assign({}, settings, data), null, 2));
	}

	static delete(key) {
		const settings = JSON.parse(readFileSync(this.filepath, 'utf8'));

		delete settings[key];

		writeFileSync(this.getFilePath(), JSON.stringify(settings, null, 2));
	}
}