微信小程序开发两个月了.大家的项目都在不断迭代.已经不是小程序.这时候就会遇到多层回调嵌套的问题.有些目不忍视了.迫不得已引入es6-promise.在微信小程序内测的时候promise不需要手动引入,后来被微信移除了.看看效果.

promise详细的介绍我就不说了.有很多大神写过.
阮一峰 promise入门

看看目录,引入es6-promise就可以用了.

1.网络请求 wxRequest.js
这里只写了get和post.
我经常会在网络请求的时候用微信原生showToast(),所以最后加了finally,方便hideToast()

var Promise = require(‘../plugins/es6-promise.js‘)

function wxPromisify(fn) {
  return function (obj = {}) {
    return new Promise((resolve, reject) => {
      obj.success = function (res) {
        //成功
        resolve(res)
      }
      obj.fail = function (res) {
        //失败
        reject(res)
      }
      fn(obj)
    })
  }
}
//无论promise对象最后状态如何都会执行
Promise.prototype.finally = function (callback) {
  let P = this.constructor;
  return this.then(
    value => P.resolve(callback()).then(() => value),
    reason => P.resolve(callback()).then(() => { throw reason })
  );
};
/**
 * 微信请求get方法
 * url
 * data 以对象的格式传入
 */
function getRequest(url, data) {
  var getRequest = wxPromisify(wx.request)
  return getRequest({
    url: url,
    method: ‘GET‘,
    data: data,
    header: {
      ‘Content-Type‘: ‘application/json‘
    }
  })
}

/**
 * 微信请求post方法封装
 * url
 * data 以对象的格式传入
 */
function postRequest(url, data) {
  var postRequest = wxPromisify(wx.request)
  return postRequest({
    url: url,
    method: ‘POST‘,
    data: data,
    header: {
      "content-type": "application/x-www-form-urlencoded"
    },
  })
}

module.exports = {
  postRequest: postRequest,
  getRequest: getRequest
}

2.微信其他API wxApi.js

var Promise = require(‘../plugins/es6-promise.js‘)

function wxPromisify(fn) {
  return function (obj = {}) {
    return new Promise((resolve, reject) => {
      obj.success = function (res) {
        //成功
        resolve(res)
      }
      obj.fail = function (res) {
        //失败
        reject(res)
      }
      fn(obj)
    })
  }
}
//无论promise对象最后状态如何都会执行
Promise.prototype.finally = function (callback) {
  let P = this.constructor;
  return this.then(
    value => P.resolve(callback()).then(() => value),
    reason => P.resolve(callback()).then(() => { throw reason })
  );
};
/**
 * 微信用户登录,获取code
 */
function wxLogin() {
  return wxPromisify(wx.login)
}
/**
 * 获取微信用户信息
 * 注意:须在登录之后调用
 */
function wxGetUserInfo() {
  return wxPromisify(wx.getUserInfo)
}
/**
 * 获取系统信息
 */
function wxGetSystemInfo() {
  return wxPromisify(wx.getSystemInfo)
}


module.exports = {
  wxPromisify: wxPromisify,
  wxLogin: wxLogin,
  wxGetUserInfo: wxGetUserInfo,
  wxGetSystemInfo: wxGetSystemInfo
}

3.用法
promise应用场景很多,下面是promise最基本的用法,在then()中returnpromise对象.
这样有效解决了回调嵌套的问题.让代码看起来更优雅.可读性更高.

var util = require(‘../../utils/util‘)
var wxApi = require(‘../../utils/wxApi‘)
var wxRequest = require(‘../../utils/wxRequest‘)
import config from ‘../../utils/config‘
//获取应用实例
var app = getApp()
Page({
  data: {
    userInfo: {}
  },
  onLoad: function () {
    var that = this;
    wx.showToast({
      title: ‘加载中‘,
      icon: ‘loading‘,
      duration: 10000
    })
    //1.获取code
    var wxLogin = wxApi.wxLogin()
    wxLogin().then(res => {
      console.log(‘1.成功了‘)
      console.log(res.code)
      var url = config.getOpenidUrl;
      var params = {
        appid: "wxed7******2d465",
        secret: "e9c5e4c******09ecc5ebd811",
        js_code: res.code,
        grant_type: "authorization_code"
      }
      //2.获取openid
      return wxRequest.getRequest(url, params)
    }).
      then(res => {
        console.log(‘2.成功了‘)
        console.log(res)
        var url = app.globalData.ip + config.searchDgUrl
        var data = util.json2Form({ phoneNumber: ‘15971908021‘ })
        //3.获取绑定手机号码
        return wxRequest.postRequest(url, data)
      }).
      then(res => {
        console.log(‘3.成功了‘)
        console.log(res)
        //4.获取系统信息
        var wxGetSystemInfo = wxApi.wxGetSystemInfo()
        return wxGetSystemInfo()
      }).
      then(res => {
        console.log(‘4.成功了‘)
        console.log(res)
        //5.获取用户信息
        var wxGetUserInfo = wxApi.wxGetUserInfo()
        return wxGetUserInfo()
      }).
      then(res => {
        console.log(‘5.成功了‘)
        console.log(res.userInfo)
        that.setData({
          userInfo: res.userInfo
        })
      })
      .finally(function (res) {
        console.log(‘finally~‘)
        wx.hideToast()
      })
  }
})

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