Simple Promise ES6

class PromiseSimple {

	constructor(executionFunction) {
		this.promiseChain = [];
		this.handleError = () => {};

		this.onResolve = this.onResolve.bind(this);
		this.onReject = this.onReject.bind(this);

		executionFunction(this.onResolve, this.onReject);
	}

	then(onResolve) {
		this.promiseChain.push(onResolve);

		return this;
	}

	catch(handleError) {
		this.handleError = handleError;

		return this;
	}

	onResolve(value) {
		let storedValue = value;

		try {
			this.promiseChain.forEach((nextFunction) => {
				storedValue = nextFunction(storedValue);
			});
		} catch(error) {
			this.promiseChain = [];
			this.onReject(error);
		}
	}

	onReject(error) {
		this.handleError(error);
	}
}

const myPromise = new PromiseSimple((onResolve, onReject) => {
	setTimeout(onResolve, 1000, 'Fine!');
});

myPromise.then((response) => {
	console.log(response);
}, (error) => {
	console.log(error);
});