Abstract:Node.js is one of the most popular technologies at present, and it is the JavaScript execution environment running on the server. With event-driven mechanism Node.js JavaScript plus high-performance V8 engine, it's easy to achieve high-performance Web services. When Node.js deals with the problem of asynchronous, it generally uses callback method, but there are Callback Hell problems in the way of callback. Whether reading or debugging is very inconvenient, it is even impossible to get the code stack. Based on Node.js platform, using Promise method, we realize a Web crawler application. We describe in detail how to use the Promise approach to deal with the problem of asynchronous callback during the application process.