Question

由于某种原因，所有功能都在同一时间返回。

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次调用_done()。 / p>

每次调用_done()时，我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);

所以日志看起来应该是

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

Answer 1

此代码生成预期输出

function preVisit(v){
    nodes[v].preVisit = visitCounter;
    visitCounter++;
}
function postVisit(v) {
    nodes[v].postVisit = visitCounter;
    visitCounter++;
}

JavaScript减少，Promise不按顺序返回

1 个答案: