Question

我想要做的是等待第二个承诺完成，连接数据，即data = data.concat(items)，然后递增计数，使循环运行指定的时间。它全部用AngularJS编写。

DataService.getSomeData().then(function(data) {
  let count = 1;
  while (count < 3) {
    if (someCondition) { // It evaluates to true

      // Second Promise
      DataService.getUserData().then(function(items) {
        data = data.concat(items); // --------> this should run before incrementing the count
      });

      count++;
    }
    $scope.myData = data;
  }
});

谢谢！

Answer 1

@Aleksey Solovey已经提到了使用$ q.all（）的解决方案，还有另一种可以使用的递归方法。

DataService.getSomeData().then(function(data) {
  getUserDataRecursion(data,0).then(result=>{
    $scope.myData = result;
  }).catch(error=>{
    console.log("error handle ",error)
  })
});


getUserDataRecursion(data,count){
  return new Promise((resolve,reject)=>{
    if(count<3){
      if (someCondition){
        DataService.getUserData().then((items) {
          data = data.concat(items);
          count++;
          getUserDataRecursion(data,count),then(()=>{
            resolve(data);
          })
        });
      }else{
        resolve(data);
      }
    }else{
      resolve(data);
    }
  })
}

Answer 2

保持api返回承诺 - 它是最容易处理和最可预测的......

  DataService.getSomeData()
    .then(someData => {
        let count = 1;
        const promises = [];

        while (count < 3) {
            if (someCondition) { // It evaluates to true
                promises.push(DataService.getUserData());
                count++;
            }
        }

        return $q.all(promises)
            .then(data => data.reduce((memo, data) => memo.concat(data), someData));
    })
    .then(data => $scope.myData = data);

如何首先执行承诺然后转到JavaScript

2 个答案: