Promiseall

> typeof new Promise((resolve, reject) => {})
'object'

GET('/user/1')
	.then((user) => {
		// do something with the response
	})

const GET = function(url) {
	return new Promise((resolve, reject) => {
		request((error, apiResponse) => {
			if (error) {
				reject(error)
			}
			resolve(apiResponse)
		})	
	})
}

class SimplifiedPromise {
	constructor(functionToBeExecuted) {
		this.promiseChain = [];
		this.handleError = () => {}; // error-handling function
	
		// With `bind`, `this` is guaranteed to be the PromiseSimple instance,
		this.onResolve = this.onResolve.bind(this);
		this.onReject = this.onReject.bind(this);
		
		functionToBeExecuted(this.onResolve, this.onReject);
	}
	
	then(handleSuccess) // adding function to the promiseChain
		push handleSucess to promiseChain
		return this promise
	catch(handleError)
		return this promise with handleError
	onResolve(value) // executed after success of functionToBeExecuted
		iterate through promise chain in try block
		call each function with the previous function's return
		call onReject(error) in catch block
	onReject(error)  // executed after failure of functionToBeExecuted
		call this promise's errorHandler
}