微信小程序中 promsie.all 与 promise 顺序执行的探究

//存储promise对象的数组

let promiseArr = [];

//图片地址数组

let imageList = [];

//将图片地址的上传的promise对象加入到promiseArr

for (let i = 0; i < imageList.length; i++) {

  let promise = new Promise((resolve, reject) => {

    //微信图片上传

    wx.uploadFile({

      url: 'https://xxx.xxx.xxx/api/uploadImage',

      filePath: imageList[i],

      name: 'file',

      success: function(res) {

        //可以对res进行处理，然后resolve返回

        resolve(res);

      },

      fail: function (error) {

        reject(error);

      },

      complete: function (res) {

      },

    })

  });

  promiseArr.push(promise)

}

//Promise.all处理promiseArr数组中的每一个promise对象

Promise.all(promiseArr).then((result) => {

  //对返回的result数组进行处理

})

//顺序处理函数

function sequenceTasks(tasks) {

  //记录返回值

  function recordValue(results, value) {

    results.push(value);

    return results;

  }

  let pushValue = recordValue.bind(null, []);

  let promise = Promise.resolve();

  // 处理tasks数组中的每个函数对象

  for (let i = 0; i < tasks.length; i++) {

    let task = tasks[i];

    promise = promise.then(task).then(pushValue);

  }

  return promise;

}

//函数数组，每个函数的返回值是一个promise对象

let promiseFuncArr = [];

//图片地址数组

let imageList = [];

//将图片地址的上传的函数加入到promiseFuncArr数组中

for (let i = 0; i < imageList.length; i++) {

  let promiseTemp = function(){

    return new Promise((resolve, reject) => {

      //微信图片上传

      wx.uploadFile({

        url: 'https://xxx.xxx.xxx/api/uploadImage',

        filePath: imageList[i],

        name: 'file',

        success: function(res) {

          //可以对res进行处理，然后resolve返回

          resolve(res);

        },

        fail: function (error) {

          reject(error);

        },

        complete: function (res) {

        },

      })

    });

  };

  promiseFuncArr.push(promiseTemp)

}

sequenceTasks(promiseFuncArr).then((result) => {

  //对返回的result数组进行处理

});

let pushValue = recordValue.bind(null, []);

promise = promise.then(task).then(pushValue);

function sequenceTasks(tasks) {

  //记录返回值

  function recordValue(results, value) {

    results.push(value);

    return results;

  }

  let pushValue = recordValue.bind(null, []);

  return tasks.reduce(function (promise, task) {

    return promise.then(task).then(pushValue);

  }, Promise.resolve());

}