Shulou(Shulou.com)05/31 Report--

This article mainly explains "how to carry out asynchronous processing in Weixin Mini Programs." Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Let's let Xiaobian take you to learn "how to process asynchronously in Weixin Mini Programs"!

Look directly at the problem:

Then look at the printed results:

According to the above two figures, it can be seen that the network request executed first in the code, and then the printed variable, but from the printed results below, the first to produce the result is to execute the function of printing variables (aafn function), and then print the data returned in the callback of network request success and the value of the assigned variable;

Why aafn is executed first and the printed value is not assigned to the top?

Because wx.request is an asynchronous request, execution of the function can continue downward while the data is requested. So here the value has not been assigned on the variable began to print the value;

How to solve this situation?

Method 1:

nested

Execute aafn function in success callback of wx.request

然后运行结果

这里就取到值了

但是如果逻辑很复杂，需要用到很多层异步，就像这样：

asyncFn1(function(){ //... asyncFn2(function(){ //... asyncFn3(function(){ //... asyncFn4(function(){ //... asyncFn5(function(){ //... }); }); }); });});

这样代码看起来就很不好看，代码的可读性和可维护性就不好了

那怎么解决这个问题呢？Promise这种概念的产生，很好地解决了这一切，Promise是什么？这里我就不多说了有兴趣的自己去看一看，Promise介绍链接

先看看Promise的方式：

function asyncFn1(){ return new Promise(function (resolve, reject) { //... })}// asyncFn2,3,4,5也实现成跟asyncFn1一样的方式...

调用

asyncFn1() .then(asyncFn2) .then(asyncFn3) .then(asyncFn4) .then(asyncFn5);

这样的话，异步函数就可以依次执行了

微信小程序的异步API怎么支持Promise呢？我们可以一个一个的用Promise去包装这些API，但是这个还是比较麻烦的。不过，小程序的API的参数格式都比较统一，只接受一个object参数，回调都是在这个参数中设置，所以，这为了统一处理提供了便利，写一个工具方法，来完成这样的工作

首先需要引用一个叫bluebird.js的文件;

进入bluebird官网下载：

这个好像是不能下载的，但是你可以点击进入，然后复制，在小程序里创建一个js文件，将代码复制到这个js里面，然后引用。

然后再写一个JS，里面写工具方法：

下面是prom.js

然后需要使用的那个页面的js里引入prom.js：

调用：

打印结果

到此，相信大家对"微信小程序中怎么进行异步处理"有了更深的了解，不妨来实际操作一番吧!这里是网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习!

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