Angular typescript中带承诺的角度调用函数

我有3个功能。我想在函数完成后调用另一个函数。在我的第一个函数中，我在页面中设置一个变量（students）。第二个函数使用这个变量。所以我用承诺。但是我尝试了很多方法。但我不能保证执行代码。我想，在我的buttonClick中，我的三个函数应该异步有序地工作。我想要下面这样的。我该怎么办

  students: [];
  studentInfoList: [];
  otherList: [];

  buttonClick() {
    const myPromise = new Promise(function (resolve, reject) {
      myFirstOperation();
    });

    myPromise()
      .then(result => {
        mySecondOperation();
      })
      .then(result => {
        myThirdOperation();
      });
  }


  myFirstOperation() {
    this.studentService.getStudents().subscribe(
      result => {
          this.students = result.data;
      });
  }

  mySecondOperation() {
    for (let student of this.students) {
      this.studentInfoList.push({ studenNameSurname=student.Name + student.Surname });
    }
  }

  myThirdOperation() {
    for (let studentInfo of this.studentInfoList) {
      this.otherList.push(this.studentInfoList);
    }
  }

---

您可以使用async/await

students: [];
  studentInfoList: [];
  otherList: [];

  async buttonClick() {
        await this.myFirstOperation();
        this.mySecondOperation();
        this.myThirdOperation();
  }


 async myFirstOperation() {
    const result = await this.studentService.getStudents().toPromise();
    this.students = result.data;

  }

  mySecondOperation() {
    for (let student of this.students) {
      this.studentInfoList.push({ studenNAmeSurname=student.Name + student.Surname });
    }
  }

  myThirdOperation() {
    for (let studentInfo of this.studentInfoList) {
      this.otherList.push(studentInfoList);
    }
  }

---

mySecondOperation

和

myThirdOperation

不执行任何异步操作，因此您可以直接编写

buttonClick() {
    this.studentService.getStudents().subscribe(
          result => {
              this.students = result.data;
              for (let student of this.students) {
                    this.studentInfoList.push({ studenNameSurname=student.Name + student.Surname });
              }
              for (let studentInfo of this.studentInfoList) {
                    this.otherList.push(this.studentInfoList);
              }
          });
}

这样试试

student = [];
studentInfoList = [];
otherList = [];

this.buttonClick().then(() => {
  this.buttonClickResult().then((data) => {        
    this.secondFunction().then(() => {
        this.thiedFunction();
    });
  });
})    

 buttonClick(){    
    return new promise((resolve , reject) => {
     // Do your stuff hear
    })
  }

buttonClickResult(){    
  return new promise((resolve , reject) => {
    this.studentService.getStudents().subscribe((result) => {
        this.student.push(...result.data);
        resolve("pass data hear"); // Pass data if you need.                                                               
    })
  })
}

secondFunction(){    
  return new promise((resolve , reject) => {
    for (let data of this.student) {
        this.studentInfoList.push({ "studenNameSurname" : data.Name + data.Surname });
    }
  })
}

thiedFunction(){
   this.otherList.push(...this.studentInfoList); 
}

---

我找到了解决办法@KrutiChoksiPatel和@Sachinsah的答案与我的答案非常接近。但它们不会起作用。因为在这个答案中，没有像下面这样的“resolve（）”函数

 buttonClick() {
    this.myFirstOperation().then(() => {
      this.mySecondOperation(() => {
        this.myThirdOperation();
      });
    });
  }

  myFirstOperation() {
    return new Promise((resolve, reject) => {
      this.studentService.getStudents().subscribe(
        result => {
          this.students = result.data;
          resolve(); //This row is important. Because of not working
        });
    })
  }

  mySecondOperation() {
    return new Promise((resolve, reject) => {
    for (let student of this.students) {
      this.studentInfoList.push({ studenNameSurname=student.Name + student.Surname });
      }
      resolve();  //This row is important. Because of not working
    })
  }

  myThirdOperation() {
    for (let studentInfo of this.studentInfoList) {
      this.otherList.push(this.studentInfoList);
    }
  }

---

也许你需要做出两个承诺。试试这个

  students: [];
  studentInfoList: [];
  otherList: [];

  buttonClick() {

    const myPromise = new Promise(function (resolve, reject) {
     this.studentService.getStudents().subscribe(
      result => {
          this.students = result.data;
          resolve();
      });
    });

    myPromise()
      .then(result => {
        mySecondOperation();
      });
  }

  mySecondOperation() {

     const my2Promise = new Promise(function (resolve, reject) {
        for (let student of this.students) {
          this.studentInfoList.push({ studenNameSurname=student.Name + student.Surname });
        }
          resolve();
     });

     my2Promise()
      .then(result => {
        myThirdOperation();
      });

  }

  myThirdOperation() {
    for (let studentInfo of this.studentInfoList) {
      this.otherList.push(this.studentInfoList);
    }

---

}

谢谢您的回复。但是，我的应用程序被很多人使用。因此，其中一些可以使用旧浏览器。async/await在旧浏览器上不起作用。所以，我想使用promise，因为它可以处理新旧浏览器@t请假定第二个和第三个函数是异步的。我只举了一个例子@sloth@HasanOzdemir然后请编辑你的问题。向这些函数返回一些东西，比如

可观察的

或

承诺

？他们需要以前方法收集的数据吗？Sachinsah没有用。它按如下顺序工作：buttonClick=>secondFunction=>thirdFunction=>buttonClickResult。但是我想要buttonClick=>buttonClickResult.=>secondFunction=>thirdFunction.@HasanOzdemir我已经根据您的流程更新了我的答案。请检查一下。谢谢您的回复@sachinsah。但这将不起作用，因为函数不调用resolve函数。我加上了工作answer@HasanOzdemir正如您所说，您需要通过resolve，所以我更新了我的答案，并且只在一个函数中设置了它。基于此，您还可以设置其他功能。谢谢您的回复@KrutiChoksiPatel。但这将不起作用，因为函数不调用resolve函数。我添加了工作答案。是的，你是对的，我会编辑它谢谢。在您的回答中，mySecondOperation有承诺，但它不是必需的，因为它对于循环来说很简单。不需要承诺，是的。我只写了第三个函数作为例子。我是为寻找三个异步函数的人写的。您可以假设第二个函数也类似于async。谢谢你的回复。

  students: [];
  studentInfoList: [];
  otherList: [];

  buttonClick() {

    const myPromise = new Promise(function (resolve, reject) {
     this.studentService.getStudents().subscribe(
      result => {
          this.students = result.data;
          resolve();
      });
    });

    myPromise()
      .then(result => {
        mySecondOperation();
      });
  }

  mySecondOperation() {

     const my2Promise = new Promise(function (resolve, reject) {
        for (let student of this.students) {
          this.studentInfoList.push({ studenNameSurname=student.Name + student.Surname });
        }
          resolve();
     });

     my2Promise()
      .then(result => {
        myThirdOperation();
      });

  }

  myThirdOperation() {
    for (let studentInfo of this.studentInfoList) {
      this.otherList.push(this.studentInfoList);
    }