Question

我使用的node.js模块有一个没有回调的方法。而不是它，有一个事件在该方法完成时触发。我希望解决一个承诺，使用该事件作为回调，确保我已成功完成该方法。

承诺上的array.lenght可以是X.所以，我需要'听'X次事件才能确保所有方法都已成功完成＆lt; - 这不是问题，我只是告诉你我知道这可能会发生

活动：

tf2.on('craftingComplete', function(recipe, itemsGained){
  if(recipe == -1){
  console.log('CRAFT FAILED')
  }
  else{
        countOfCraft++;
    console.log('Craft completed! Got a new Item  #'+itemsGained);
  }
})

无极：

const craftWepsByClass = function(array, heroClass){
        return new Promise(function (resolve, reject){

            if(array.length < 2){
                console.log('Done crafting weps of '+heroClass);
                return resolve();
            }
            else{
                for (var i = 0; i < array.length; i+=2) {
                    tf2.craft([array[i].id, array[i+1].id]); // <--- this is the module method witouth callback
                }
        return resolve(); // <---- I want resolve this, when all tf2.craft() has been completed. I need 'hear' event many times as array.length
            }   

        })
}

Answer 1

如果事件的触发顺序与导致它们的相应craft()调用的顺序相同，则可以使用队列：

var queue = []; // for the tf2 instance
function getNextTf2Event() {
  return new Promise(resolve => {
    queue.push(resolve);
  });
}
tf2.on('craftingComplete', function(recipe, itemsGained) {
  var resolve = queue.shift();
  if (recipe == -1) {
    resolve(Promise.reject(new Error('CRAFT FAILED')));
  } else {
    resolve(itemsGained);
  }
});

function craftWepsByClass(array, heroClass) {
  var promises = [];
  for (var i = 1; i < array.length; i += 2) {
    promises.push(getNextTf2Event().then(itemsGained => {
      console.log('Craft completed! Got a new Item  #'+itemsGained);
      // return itemsGained;
    }));
    tf2.craft([array[i-1].id, array[i].id]);
  }
  return Promise.all(promises).then(allItemsGained => {
    console.log('Done crafting weps of '+heroClass);
    return …;
  });
}

如果您对事件的顺序一无所知，并且可能有多个并发呼叫craftWepsByClass，则无法避免全局计数器（即与tf2链接的全局计数器实例）。缺点是例如在两个重叠的来电a = craftWepsByClass(…), b = craftWepsByClass()中，a承诺无法解决，直到完成第二个电话的制作。

var waiting = []; // for the tf2 instance
var runningCraftings = 0;
tf2.on('craftingComplete', function(recipe, itemsGained) {
  if (--runningCraftings == 0) {
    for (var resolve of waiting) {
      resolve();
    }
    waiting.length = 0;
  }
  if (recipe == -1) {
    console.log('CRAFT FAILED')
  } else {
    console.log('Craft completed! Got a new Item  #'+itemsGained);
  }
});

function craftWepsByClass(array, heroClass) {
  for (var i = 1; i < array.length; i += 2) {
    runningCraftings++;
    tf2.craft([array[i-1].id, array[i].id]);
  }
  return (runningCraftings == 0
    ? Promise.resolve()
    : new Promise(resolve => {
        waiting.push(resolve);
      })
  ).then(() => {
    console.log('Done crafting weps of '+heroClass);
  });
}

当然，在这两种解决方案中，您必须100％确定每次调用craft()只会导致一个事件。

Answer 2

首先让我们宣传制作：

function craft(elem){
 //do whatever
 return Promise((resolve,reject) => 
  tf2.on('craftingComplete', (recipe,itemsGained) => 
   if( recipe !== -1 ){
     resolve(recipe, itemsGained);
   }else{
    reject("unsuccessful");
   }
  })
);
}

因此，为了制作倍数，我们将数组映射到promises并使用Promise.all：

Promise.all( array.map( craft ) )
 .then(_=>"all done!")

Answer 3

您可以查看event-as-promise包。它将事件转换为Promise 持续，直到完成所有事件处理。

与async / await结合使用时，您可以轻松地使用事件编写for循环或while循环。例如，我们希望处理data事件，直到它返回null。

const eventAsPromise = new EventAsPromise();

emitter.on('data', eventAsPromise.eventListener);

let done;

while (!done) {
  const result = await eventAsPromise.upcoming();

  // Some code to process the event result
  process(result);

  // Mark done when no more results
  done = !result;
}

emitter.removeListener('data', eventAsPromise.eventListener);

如果你精通发电机功能，它可能看起来有点简单。

const eventAsPromise = new EventAsPromise();

emitter.on('data', eventAsPromise.eventListener);

for (let promise of eventAsPromise) {
  const result = await promise;

  // Some code to process the event result
  process(result);

  // Stop when no more results
  if (!result) {
    break;
  }
}

emitter.removeListener('data', eventAsPromise.eventListener);

Answer 4

我需要检查事件'craftingComplete'是否像我一样多次触发致电tf2.craft。没有任何可能的身份证或工艺失败。我需要知道tf2.craft是否已经完成，只有为什么要检查 'craftingComplete'事件

鉴于我们知道Function unlock_conns() Dim conn For Each conn In ActiveWorkbook.Connections Select Case conn.Type Case xlConnectionTypeOLEDB conn.OLEDBConnection.MaintainConnection = False Case xlConnectionTypeODBC conn.ODBCConnection.MaintainConnection = False End Select Next conn End Function圈内的i for将增加i += 2 i小于.length array，我们可以在for循环之前创建一个等于该数字的变量，并将i与事件处理程序中的数字进行比较

const craftWepsByClass = function(array, heroClass) {
  return new Promise(function(resolve, reject) {

    var countCraft = 0;
    var j = 0;
    var n = 0;
    for (; n < array.length; n += 2);

    tf2.on('craftingComplete', function(recipe, itemsGained) {
      if (recipe == -1) {
        console.log('CRAFT FAILED')
      } else {
        countOfCraft++;
        console.log('Craft completed! Got a new Item  #' + itemsGained);
        if (j === n) {
          resolve(["complete", craftCount])
        }
      }
    })

    if (array.length < 2) {
      console.log('Done crafting weps of ' + heroClass);
      return resolve();
    } else {
      try {
        for (var i = 0; i < array.length; i += 2, j += 2) {
          tf2.craft([array[i].id, array[i + 1].id]);
        }
      } catch (err) {
        console.error("catch", err);
        throw err
      }
    }

  })
}

craftWepsByClass(array, heroClass)
.then(function(data) {
  console.log(data[0], data[1])
})
.catch(function(err) {
  console.error(".catch", err)
})

等待事件以解决承诺

4 个答案: