方法N由條件

Question

每次對象我有下一個對象的結構：

{ 
1698452536:Object {url: "1", isProcessed: false} 
1701673991:Object {url: "2", isProcessed: false} 
1717724454:Object {url: "3", isProcessed: false} 
1756233961:Object {url: "4", isProcessed: false} 
1797093325:Object {url: "5", isProcessed: false} 
1857721095:Object {url: "6", isProcessed: false} 
2095153396:Object {url: "7", isProcessed: false} 
2098466246:Object {url: "8", isProcessed: false} 
2131427779:Object {url: "9", isProcessed: false} 
89975:Object {url: "10", isProcessed: false} 
21591836:Object {url: "11", isProcessed: false} 
80794211:Object {url: "12", isProcessed: false} 
116460496:Object {url: "13", isProcessed: false} 
159798435:Object {url: "14", isProcessed: false} 
223366448:Object {url: "15", isProcessed: false} 
361352239:Object {url: "16", isProcessed: false} 
498790092:Object {url: "17", isProcessed: false} 
508072650:Object {url: "18", isProcessed: false} 
514973525:Object {url: "19", isProcessed: false} 
560440401:Object {url: "20", isProcessed: false} 
} 

我需要每次只有前五個完成後處理五個內部對象採取另外五個。 有沒有辦法做這種實現？

UPDATE：

I`d嘗試下面的代碼以改造對象來分塊陣，而是如何通過批量異步和呼叫僅散滿後大部分是成功採取另一種？

chunkArray(Object.values(images),5).forEach((array)=>{}); 
function chunkArray(array, groupsize) { 
var sets = [], 
    chunks, i = 0; 
chunks = array.length/groupsize; 

while (i < chunks) { 
    sets[i] = array.splice(0, groupsize); 
    i++; 
} 
return sets; 

}

Answer 1

使用Object.keys讓所有對象的關鍵作爲一個數組，然後你可以做陣列解決方案：

var objs = { 
    1698452536:Object {url: "1", isProcessed: false} 
    1701673991:Object {url: "2", isProcessed: false} 
    1717724454:Object {url: "3", isProcessed: false} 
    1756233961:Object {url: "4", isProcessed: false} 
    1797093325:Object {url: "5", isProcessed: false} 
    1857721095:Object {url: "6", isProcessed: false} 
    2095153396:Object {url: "7", isProcessed: false} 
    2098466246:Object {url: "8", isProcessed: false} 
    2131427779:Object {url: "9", isProcessed: false} 
    89975:Object {url: "10", isProcessed: false} 
    21591836:Object {url: "11", isProcessed: false} 
    80794211:Object {url: "12", isProcessed: false} 
    116460496:Object {url: "13", isProcessed: false} 
    159798435:Object {url: "14", isProcessed: false} 
    223366448:Object {url: "15", isProcessed: false} 
    361352239:Object {url: "16", isProcessed: false} 
    498790092:Object {url: "17", isProcessed: false} 
    508072650:Object {url: "18", isProcessed: false} 
    514973525:Object {url: "19", isProcessed: false} 
    560440401:Object {url: "20", isProcessed: false} 
}; 

var keys = Object.keys(objs); 

for (var i = 0; i < keys.length; i += 5) { 
    // Do something on every five keys  
} 

Answer 2

下列基於承諾的解決方案轉移批量n = 5個項目到您的異步回調函數並在回調信號完成後立即繼續：

// Process items in batches of size n via callback cb: 
 
function process(items, n, cb, offset = 0) { 
 
    if (offset >= items.length) return; 
 
    new Promise((resolve, reject) => { 
 
    cb(items.slice(offset, offset + n), resolve, reject); 
 
    }).then(() => process(items, n, cb, offset + n)); 
 
} 
 

 
// Example: 
 
let items = [0,1,2,3,4,5,6,7,8,9,10,11,12]; 
 

 
process(items, 5, (batch, resolve) => { 
 
    console.log("processing " + batch); 
 
    setTimeout(resolve, 1000); // Async processig... 
 
});

如果您的異步回調一次只能處理一個項目，則可能需要創建5個promise並在遞歸到下一個批處理之前等待至all have resolved。

Answer 3

這是您需要的骨架。我嘗試以可以自我解釋的方式命名函數和變量。

'use strict'; 
 

 
let toProcess = { 
 
\t '1698452536': { url: "1", isProcessed: false }, 
 
\t '1701673991': { url: "2", isProcessed: false }, 
 
\t '1717724454': { url: "3", isProcessed: false }, 
 
\t '1756233961': { url: "4", isProcessed: false }, 
 
\t '1797093325': { url: "5", isProcessed: false }, 
 
\t '1857721095': { url: "6", isProcessed: false }, 
 
\t '2095153396': { url: "7", isProcessed: false }, 
 
\t '2098466246': { url: "8", isProcessed: false }, 
 
\t '2131427779': { url: "9", isProcessed: false }, 
 
\t '89975': { url: "10", isProcessed: false }, 
 
\t '21591836': { url: "11", isProcessed: false }, 
 
\t '80794211': { url: "12", isProcessed: false }, 
 
\t '116460496': { url: "13", isProcessed: false }, 
 
\t '159798435': { url: "14", isProcessed: false }, 
 
\t '223366448': { url: "15", isProcessed: false }, 
 
\t '361352239': { url: "16", isProcessed: false }, 
 
\t '498790092': { url: "17", isProcessed: false }, 
 
\t '508072650': { url: "18", isProcessed: false }, 
 
\t '514973525': { url: "19", isProcessed: false }, 
 
\t '560440401': { url: "20", isProcessed: false } 
 
}; 
 

 
let howManyItemsInConcurrency = 5; 
 
stackProcessing(toProcess, howManyItemsInConcurrency); 
 

 
function stackProcessing(stack, concurrency){ 
 
\t let objsToProcess = Object.keys(stack).filter(objKey => !stack[objKey].isProcessed).slice(0, concurrency); 
 
\t if(!objsToProcess.length){ 
 
\t \t return console.log('Finish!'); 
 
\t } 
 

 
\t let objsBeingProcessed = objsToProcess.map(objKey => objProcessing(stack[objKey])); 
 
\t Promise.all(objsBeingProcessed) 
 
\t \t .then(result => { 
 
\t \t \t console.log('result', result); 
 
\t \t \t stackProcessing(stack, concurrency); 
 
\t \t }); 
 
} 
 

 

 
function objProcessing(obj){ 
 
\t console.log(`Processing URL: ${obj.url}`); 
 
\t return new Promise((resolve, reject) => { 
 
\t \t // Simulating some async processing happening 
 
\t \t setTimeout(() => { 
 
\t \t \t obj.isProcessed = true; 
 
\t \t \t resolve(obj); 
 
\t \t }, 1000); 
 
\t }); 
 
}

Answer 4

感謝@Diego ZoracKy，他的回答我提供依據來解決這個問題。

let processImages =() => { 
        let itemToDo = Object.values(images).filter((item) => { return !item.isProcessed }).slice(0, 5); 
        if (itemToDo.length) { 
         async.map(itemToDo, (arrayItem, callback) => { 
           try { 
            imagesize(arrayItem.url).then((result) => { 
             return callback(null, result); 
            }).catch(function(err) { 
             return callback(err); 

           } catch (e) { 
            return callback(err); 
           } 
          }, 
          (errors, results) => { 
           results.forEach((result) => { 
            ... 
           }); 
           if (errors) {          
       console.log('error', '!!!!!!!!!Exception was caught!!!!!! '); 
           } 
           processImages(); 
          } 
         ) 
        } else { 
         //CONTINUE TO NEXT URL 
         } 
       } 
       //Invoke process images function first time 
      processImages();