promise chaining

Original address: http://www.cnblogs.com/dojo-lzz/p/4340897.htmlResolve callback functions nested too deep, parallel logic must be executed serially, a promise represents the end result of an asynchronous operation, the main way to interact with promise is to register the callback function with his then () method to receive the final result value of promisePromise related protocols are Promisea and promisea

-- Address: http://blog.chrisyip.im/nodejs-101-package-promise-and-async First, let's review the Sagase project structure: lib/ cli.js sagase.jsGruntfile.jspackage.json I spoke about it in the previous article.package.json, This articlelib/sagase.js. Because the code is relatively long, we will talk about it separately in one section. For the complete code, open GitHub. 'use strict'; Notifies the compiler to enter strict mode. The main function

1. Introduction The Promise object is a specification proposed by the CommonJS workgroup to provide a unified interface for asynchronous Operations. first, It is an object, and secondly, it acts as an intermediary between an asynchronous operation and a callback Function.simply put, the idea is that every asynchronous task immediately returns a promise object, and because it returns immediately, it can take

The previously adopted Axios is based on promise, but our dear and maverick ie does not have a built-in promise, so install a promise plugin in advance:NPM Install Promise @7.1.1Import Promise from ' Promise ';if (!window.

Promise is being used more and more widely in JavaScript, especially in the JavaScript of server side, such as node. JS programming. Although promise has its own problems, it has its unique advantages in solving multiple nested callback and other problems.Promise common scenes are basically in the server side, but in fact, in the client side, it also has a useful, but currently more rare.As a good client si

The future is used to get the results of an asynchronous operation, while promise is more abstract and cannot directly guess its function.FutureThe future comes first from the JDK's java.util.concurrent.Future, which is used to represent the result of an asynchronous operation.The result of the operation can be obtained through the Get method, and if the operation is not completed, the thread that is currently called is synchronized, and if blocking i

Tag: The CREATE call ONS ack this pre intent callbackBasic understandingThe core value of promise is to create an asynchronous execution process and give you the opportunity to clean up.Promise object One but the creation is executed immediately, the execution process is asynchronous, and the subsequent logic is not blocked.Direct declaration, immediate execution let promise = new

code structure is greatly tuned, and promises is able to cope with this change easily. When the time is right I will make a detailed comparison, first of all let us begin to understand promises quickly. What is promises?The promises symbolizes the end result of an asynchronous operation. Promises interaction mainly through its then method, then method accepts a callback function, which accepts the return value of successful execution or the cause of failure, the error is generally the wro

Advantages: In the process of asynchronous execution, the code that executes the code and the result is clearly separated (because the Promise object has a chained notation, then and catch) Combined with promise, many asynchronous tasks can be combined in parallel and serially. Example 1. Generates a random number between 0-2 and, if less than 1, waits for a period of time to r

Recently saw a lot of articles are talking about promise, why Asynchronous Programming now receive so much attention? And why asynchronous programming to choose Promise ?First of all, the reason why asynchronous programming is so important is that JavaScript is moving towards standardization, normalization (MVC, module, OOP), so some of the normative constraints in traditional programming areas are becoming

First, rx.js understanding Rx.js is a function-responsive programming, observable, SUBJECT, observer is the implementation of its external delivery. Observable is actually promise++ (Promise object is used to perform an asynchronous operation). In the Rx, you can simply convert a Promise to a observable, just need: var stream = Rx.Observable.fromPromise (

About the Promise mode: The promise mode is in one of the following three states at any time: Incomplete (unfulfilled) completed (resolved) rejection (rejected) The then method on the Promise object, as defined by the CommonJS promise/a Standard, is responsible for adding handler functions

1. Deferred object:It is generally declared inside a function and changes its state during operation, such as success or failure, and eventually returns the Promise object for state monitoring.Main methods:Deferred. Resolve (param ...) : Successful execution will trigger the done callback method for the Promise object.Deferred. Reject (param ...) : Execution failure will trigger the fail callback method for

Difference between Deferred and promise in jQuery, jquerydeferred What is the difference between Deferred and Promise? Promise A promise is an object returned by an asynchronous function. When you want to write such a function, you need to use a deferred. var promise = $.aja

Use Promise of jQuery and jQueryPromise Promise has been widely used in javascript, especially server side javascript, such as Node. js programming. Although Promise has its own problems, it still has its unique advantages in solving multi-layer nested callback and other problems. Common scenarios of Promise are basica