validate-password.js

// provided a string (password)
function validatePassword(password) {
	// create promise with resolve and reject as params
	return new Promise((resolve, reject) => {
		// validate that password matches bambi (the deer)
		if (password !== 'bambi') {
			// password doesn't match, return an error with reject
			return reject('Invalid Password!');
		}

		// password matches, return a success state with resolve
		resolve();
	});
}

function done(err) {
	// if an err was passed, console out a message
	if (err) {
		console.log(err);
		return; // stop execution
	}

	// console out a valid state
	console.log('Password is valid!');
}

// dummy password
const password = 'foo';

// using a promise, call the validate password function
validatePassword(password)
	.then(() => {
		// it was successful
		done(null);
	})
	.catch(err => {
		// an error occurred, call the done function and pass the err message
		done(err);
	});