遵守承诺不会按顺序返回的JavaScript减少

问题描述：

由于某些原因，所有函数都在同一时间返回。遵守承诺不会按顺序返回的JavaScript减少

我想等待第一个函数解析，然后在调用第二个函数之前调用_done()，然后调用_done()，然后调用第三个函数，然后再调用_done()。

每次调用_done()我想传递已解析的值从前面的函数调用。

"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);

那么日志应该像

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

'const func = this [action.functionToCall]（action.argumentToSend）;'已经调用函数。我确信这不是你想到的。 – Tomalak

你的代码如何期待'resolvedFromOne/Two/Three'被记录？ –

获得期望的方式就像https://jsfiddle.net/LoL119ep/ –

答

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);

遵守承诺不会按顺序返回的JavaScript减少

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