ES6 denodeify

denodeify.js

const denodeify = (fn) =>
	function (...args) {
		// bind our node function to the current context with arguments
		const boundFn = fn.bind(this, ...args);

		return new Promise((resolve, reject) => {
			// call our bound node-style function
			// typical node-style is `callback (err, result)`
			// but we can account for more arguments
			// by using a spread
			boundFn((err, ...results) =>
				// if an err, reject, otherwise resolve with results
				(err) ? reject (err) : resolve (...results)
			);
		});
	};
	
// Short version:
const denodeify = (fn) => function (...args) { 
	const boundFn = fn.bind(this, ...args);
	return new Promise((resolve, reject) => { 
		boundFn((err, ...results) => (err) ? reject (err) : resolve (...results) );
	});
};