定义： Promise then 返回一个新的 promise。其实上 double方法 返回一个 int类型，increment 返回一个Promise对象double 返回类型与定义不符合，这其中Promise做了什么？是 return new Promise(function(resolve,reject){resolve(value*2)})?那Promise 如何区别return int，string，Promise 做 … Assuming that you have a basic understanding about JavaScript Promises, I’ll start by creating a method which returns a Promise, so that you can see how to return data from promise. The recommended method to interact via a Http service is by creating an intermediate service which has the responsibly of communicating with the API and converting the raw data into one or more domain models. Essentially, we can "synchronize" a call to multiple asynchronous operations in succession. I tried using resolve but I’m not sure if it works like this. A promise chain sounds complex, but it's fundamentally simple. We're using a promise chain in the above example to create a chain of actions to be called one after another. In this lecture we handled asynchronous code by using promises. By converting the observab… Each call to then() is called with the previous then() function's return value. I’m trying to get some values from local storage but I can’t figure out how to return a value from a promise. In this tutorial, you’ll learn how to return data from JavaScript Promise. Getting Type Safety for TypeScript Promises Posted 21st November 2017 21st November 2017 Steve Fenton This one has cropped up a couple of times and I’m interested in this kind of problem. I would like to have the storage getter inside a function so I can call it when needed, everything I try results in a pending state from the promise.