吊装或回调问题？在writeLog（）之前完成（循环），但在完成之前完成日志写入

Question

我试图循环播放一组队列以获取播放器数据并将数据传递给对象。我的ajax调用获取文件。在通过所有团队循环之后，我想用收集的数据编写日志。问题是，writeLog（）立即调用 - 我认为 - 不等待循环完成。这是一个悬挂问题吗？回调问题？如何在for循环完成后重构我的代码以写入Log（）？

(function(){ 

$('#generate-report').on('click', function(){ 

    var logObj = { 
     playerCount: 0, 
     firstNameArray: [], 
     lastNameArray: [], 
     firstNameCharCount: 0, 
     lastNameCharCount: 0, 
     resultFirst: 0, 
     resultLast: 0, 
     freqReportFirst: "First name\n", 
     freqReportLast: "Last name\n", 
     freqObjFirst: {}, 
     freqObjLast: {},   
    } 

    var url = "http://feeds.nfl.com/feeds-rs/roster/"; 

    var teams = new Array("3800", "0200", "0325", "0610", "0750", "0810", "0920", "1050", 
          "1200", "1400", "1540", "1800", "2120", "2200", "2250", "2310", 
          "2700", "3000", "3200", "3300", "3410", "3430", "2520", "3700", 
          "3900", "4400", "4600", "4500", "2510", "4900", "2100", "5110" 
            ); 
    //var teams = new Array("3800"); // For testing 

    for(var i=0; i<teams.length; i++){ 
     console.log(teams[i]); 
     $.ajax({ 
      url: url + teams[i] + ".json", 
      type: 'GET', 
      success: function(response){ 
       processPlayerNames(response, logObj); 
      }, 
      error: function(response){ 
       console.log(response); 
      } 
     }); 
    }; 

    writeLog(logObj); 

}); 

}）（）;

Answer 1

$.ajax()异步返回结果。你可以把$.ajax()呼叫到一个数组，然后用Promise.all()，.map()上承诺的对象数组，或者使用$.when()，Function.prototype.apply()，.map()调用在.then()writeLog()链可变表示jQuery的承诺对象之前完成所有的异步任务与$.when()调用返回。

var requests = $.when.apply(null, teams.map(function(team) { 
    return $.ajax({ 
      url: url + team + ".json", 
      type: 'GET', 
      success: function(response){ 
       processPlayerNames(response, logObj); 
      } 
     }); 
})); 

requests.then(function() { 
    writeLog(logObj) 
}, function(response){ 
    console.log(response); 
});