Programming VIP

In fact, before the emergence of ES6 standard, the community first put forward the Promise scheme. Later, with the addition of ES6, its usage was unified and native Promise objects were provided. Promise basic information If you have to explain what Promise is, it is simply a container that holds the results of an event (usually asynchronou ...

preface Promise is a very common concept in front-end interview and work. There is also a market for the handwritten implementation of its various methods. Today, I will summarize the simple implementation of promise's basic methods. catch() method The catch method is an encapsulation of the then method and is only used to receive error messag ...

causeThe project needs to do an upload function, which uploads 20 videos at a time. There will be a blocking problem if it is not transmitted directly.Because a web page can only have 6 tcp connections with the same domain name at most. If you do not control the concurrent transmission of 6 interfaces at the same time, all subsequent operations ...

Promise introduction Promise asynchronous programming solution is more reasonable and powerful than the traditional solution (callback function), mainly to solve the problem of callback hell. What is hell? Look at the following code: doSomething(function(result) { doSomethingElse(result, function(newResult) { doThirdThing(newResult, fu ...

This paper understands Promise principle by implementing a simple class, compares Promise with traditional callback, shows Promise's advantages in asynchronous programming, and finally introduces Promise's application in practical development. I concept Promise decouples asynchronous operations from callbacks and associates them through execu ...

Node.js MySQL driver Node. The native MySQL driver library of JS is called mysql MySQL L2 project is an upgraded version of the native MySQL driver project. It is compatible with MySQL and supports its main features. It provides new features: Faster and better performancePreprocessing statementExtended support for encoding and collati ...

1. promise object value promiseResult A property in promise object: [promiseResult] Save the results of the success or failure of the object This value is manipulated by the resolve and reject functions if (xhr.readyState === 4) { if (xhr.status >= 200 && xhr.status < 300) { resolve(xhr.response) ...