javascript - 如何串联 promise

我想将一系列的诺言链接起来，以便依次执行三个诺言。我不想嵌套功能。我尝试向其中添加一个解析，但似乎在功能内部的所有操作完成之前它都已解析。

function first(){
  var promise = new Promise(function(resolve, reject){
            console.log('fetchToken 1');
  });
  return promise;
}

function second(item){
  var promise = new Promise(function(resolve, reject){
            console.log('fetchToken 2');
  });
  return promise;
}

function third(item){
  var promise = new Promise(function(resolve, reject){
            console.log('fetchToken 3');
  });
  return promise;
}

  function getTokenGroup() {
    function logTaskError(e) {
        console.error(e);
        throw e;  // reject the Promise returned by then
    }
    var task1 = first();
    var task2 = task1.then(second);
    var task3 = task2.then(third);
    var alltasks = task3.then(null, logTaskError);

    return alltasks;
  }

  getTokenGroup();

最佳答案

您需要致电“解决”：

 function first(){
    var promise = new Promise(function(resolve, reject){
      console.log('fetchToken 1');
      resolve(1); //==> call this one, parameter in here is just a sample
    });
    return promise;
  }

  function second(item){
    var promise = new Promise(function(resolve, reject){
      console.log('fetchToken 2');
    });
    return promise;
  }

  function third(item){
    var promise = new Promise(function(resolve, reject){
      console.log('fetchToken 3');
    });
    return promise;
  }

  function getTokenGroup() {
    function logTaskError(e) {
      console.error(e);
      throw e;  // reject the Promise returned by then
    }
    var task1 = first();
    var task2 = task1.then(second);
    var task3 = task2.then(third);
    var alltasks = task3.then(null, logTaskError);

    return alltasks;
  }

  getTokenGroup();

关于javascript - 如何串联 promise ，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/43578221/