JavaScript 减少承诺不按顺序返回

Bill 发表于 Dev

账单

出于某种原因，所有函数都同时返回。

我想等待第一个函数解析然后_done()在调用第二个函数之前调用，然后调用_done()然后调用第三个函数然后_done()再次调用。

每次_done()调用时，我都想传递从前一个函数调用中解析的值。

"use-strict"

function _test(actions){
    return actions.reduce((chain, action) => {
      const func = this[action.functionToCall](action.argumentToSend);
      return chain.then(() => func()).then(val => console.log(val));
    }, Promise.resolve().then(val => _done()));
}

function _one(data){
    return new Promise((resolve, reject) => {
      setTimeout(function(){  
        console.log(data); 
        resolve();
      }, 2000);
    })
}

function _two(data){
    return new Promise((resolve, reject) => {
        setTimeout(function(){  
          console.log(data); 
          resolve();
        }, 2000);
    })
}

function _three(data){
    return new Promise((resolve, reject) => {
        setTimeout(function(){  
          console.log(data); 
          resolve();
        }, 2000);
    })
}

function _done(data){
  console.log(data);
}

const arrayOfObjects = [
    { functionToCall: '_one', argumentToSend: 'Yay function one was called with this argument' },
    { functionToCall: '_two', argumentToSend: 'Yay function two was called with this argument' },
    { functionToCall: '_three', argumentToSend: 'Yay function three was called with this argument' },
    ];

_test(arrayOfObjects);

所以日志应该看起来像

Yay function one was called with this argument
resolvedFromOne
Yay function two was called with this argument
resolvedFromTwo
Yay function three was called with this argument
resolvedFromThree

雅罗曼达 X

此代码产生预期的输出

    function _test(actions){
        return actions.reduce((chain, action) => {
          return chain.then(() => action.functionToCall(action.argumentToSend)).then(val => console.log(val));
        }, Promise.resolve());
    }
    
    function _one(data){
        return new Promise((resolve, reject) => {
          setTimeout(function(){  
            console.log(data); 
            resolve('resolvedFromOne');
          }, 2000);
        })
    }
    
    function _two(data){
        return new Promise((resolve, reject) => {
            setTimeout(function(){  
              console.log(data); 
              resolve('resolvedFromTwo');
            }, 2000);
        })
    }
    
    function _three(data){
        return new Promise((resolve, reject) => {
            setTimeout(function(){  
              console.log(data); 
              resolve('resolvedFromThree');
            }, 2000);
        })
    }
    
    // not required
    function _done(data){
      console.log(data);
    }
    
    const arrayOfObjects = [
        { functionToCall: _one, argumentToSend: 'Yay function one was called with this argument' },
        { functionToCall: _two, argumentToSend: 'Yay function two was called with this argument' },
        { functionToCall: _three, argumentToSend: 'Yay function three was called with this argument' },
        ];
    
    _test(arrayOfObjects);

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