Node.js EventLoop操作未完成？

Question

這對於一個節點/快速/ MongoDB的應用程序，用AJAX調用

出於某種原因，一個selector.html(）事件被替換 選擇的HTML，但現在還不是。

唯一的變化是引入在後端的editAll()功能，它傳遞.get MongoDB的數據，阿賈克斯將其傳送到前端之前做一些計算。

取而代之的是瀏覽器的控制檯，每個btn.click

[13:47:57.240] GET http://localhost:9999/ [HTTP/1.1 200 OK 5ms] 
[13:47:57.174] "Getting All Actions" 
[13:47:57.192] "value of action with index 0 = 4" 
[13:47:57.193] "value of action with index 1 = 8" 
[13:47:57.193] "value of action with index 2 = 9" 
[13:48:03.704] GET http://localhost:9999/ [HTTP/1.1 200 OK 7ms] 
[13:48:03.640] "Getting All Actions" 
[13:48:03.661] "value of action with index 0 = 4" 
[13:48:03.661] "value of action with index 1 = 8" 
[13:48:03.661] "value of action with index 2 = 9" 

..the控制檯寫GET http://localhost:9999/的寫了一個全套的「迴應」，一組重複的div出現在前端

[13:29:24.244] GET http://localhost:9999/ [HTTP/1.1 200 OK 5ms] 
[13:29:24.182] "Getting All Actions" 
[13:29:24.197] "value of doc with index 0 = 24" 
[13:29:24.197] "value of doc with index 1 = 28" 
[13:29:24.197] "value of doc with index 2 = 29" 
... 
[13:29:24.198] "value of doc with index 6 = 24" 
[13:29:24.198] "value of doc with index 7 = 28" 
[13:29:24.199] "value of doc with index 8 = 29" 

據我所知，後端工作正常，因爲唯一的3 docs in the db傳遞給eventAll（）函數，該函數再次提供相同的3 docs。

function getAll(res) { 

    db.collection('demo').find().sort({ value: 1 }).toArray(function (err, docs) { 
     console.log("Got the docs: " + utils.inspect(docs)); 

     //res.json({docs: docs}); THIS WORKS PERFECTLY, 
            but the eventAll() pass causes this frontend issue 

      /* pass and rebuild the data array before we 'json' it */ 
     var editedDocs = editAll(docs); 
     res.json({docs: editedDocs}); 

    }); 
} 

一個名爲傳遞數據的editAll（）函數，是事件循環操作沒有不散的東西？

function editAll(allDocs) { 
    var returnedValue = []; 
    for (var i=0, len=allDocs.length; i < len; ++i){ 
     //does some calculations 
    var newVal = {_id:allDocs[i]._id,title:allDocs[i].title,value:allDocs[i].value}; 
    returnedValue.push(newVal); 
    } 
    console.log(returnedValue); 
    return (returnedValue); 
} 

爲什麼每一個btn.click是要添加另一組的div來#result

這裏的AJAX不用彷徨調用基礎上btn.click一些HTML，通過gotAllSuccess

$('#getBtn').click(function() { 
    console.log('Getting All'); 
    $.get('http://localhost:9999'). 
    done(gotAllSuccess). 
    fail(gotAllFailure); 
}); 

function gotAllSuccess(result){ 

    var docs = result.docs; 
    var html = ''; 
    var doc; 
    for (var i=0, len=docs.length; i < len; i++){ 
    doc = docs[i]; 
     console.log("value of doc with index " + i + " = " + doc.value); 
    html += "<div class='rResult' id='rResult" + i + "'>"+doc.title+"</div><br>"; 
    } 
    $('#result').html(html); 
} 

Answer 1

基本上，你的代碼是可以的，並且必須按照預期工作。 我建議您在將其寫入響應之前檢查邏輯值並記錄editedDocs值。

看來，你以某種方式查詢結果是緩衝。

您可以重寫editAll功能如下（以消除環路和所有其他變量，以及所有可能副作用）：

function editAll(allDocs) { 
    return allDocs.map(function(it){ 
     return { 
      _id:it._id, 
      title:it.title, 
      value:it.value 
     } 
    }) 
}