Question

当我打印整个数组时，它是print.but如果我尝试逐个元素打印它打印为undefined.this是我的功能。我在函数末尾打印数组。客户端函数用于连接ajax API.i试图通过ajax函数获取与数据库中特定字符串匹配的整数id，并将它们推送到两个数组中。

function fetch() {
var arrayForClass = [];//this is a array get undefined at the end
var arrayForMessage = [];//this is a array get undefined at the end
exceptionPattern ="";
receivedData.length = 0;
var queryInfo;
var queryForSearchCount = {
    tableName: "LOGANALYZER",
    searchParams: {
        query: "_eventTimeStamp: [" + from + " TO " + to + "]",
    }
};

client.searchCount(queryForSearchCount, function (d) {
    if (d["status"] === "success" && d["message"] > 0) {
        var totalRecordCount = d["message"];
        queryInfo = {
            tableName: "LOGANALYZER",
            searchParams: {
                query: "_eventTimeStamp: [" + from + " TO " + to + "]",
                start: 0, //starting index of the matching record set
                count: totalRecordCount //page size for pagination
            }
        };
        client.search(queryInfo, function (d) {
             var obj = JSON.parse(d["message"]);
             if (d["status"] === "success") {
                 for (var i = 0; i < obj.length; i++) {
                     if(obj[i].values._level === "ERROR" || obj[i].values._level === "WARN"){
                         receivedData.push([{
                             date: new Date(parseInt(obj[i].values._eventTimeStamp)).toUTCString(),
                             level: obj[i].values._level,
                             class: obj[i].values._class,
                             content: obj[i].values._content,
                             trace: (obj[i].values._trace ? obj[i].values._trace : ""),
                             timestamp: parseInt(obj[i].values._eventTimeStamp)
                         }]);
                     }else{
                         continue;
                     }
                 }
                 console.log(receivedData);
                 for (forLoopI = 0; forLoopI < receivedData.length; forLoopI++){
                     var className = receivedData[forLoopI][0].class;
                     var strclassname = className.toString();
                     var messageContent = receivedData[forLoopI][0].content;
                     queryInfo = {
                         tableName: "EXCEPTION_CLASS_FOR_ERROR_PATTERNS",
                         searchParams: {
                             query: "class_name: "+ strclassname + "",
                             start: 0, //starting index of the matching record set
                             count: 1 //page size for pagination
                         }
                     };
                     client.search(queryInfo,function(d){
                         var obj = JSON.parse(d["message"]);
                         if (d["status"] === "success") {
                             var num = obj[0].values.id;
                             var strnum = num.toString();
                             arrayForClass.push(strnum);
                         }else{
                                 $(canvasDiv).html(gadgetUtil.getCustemText("No content to display","error while creating the error pattern" +
                                 " please try again"));
                         }
                     },function(error){
                          console.log(error);
                          error.message = "Internal server error while data indexing.";
                          onError(error);
                     });
                     queryInfo = {
                          tableName: "ERROR_MESSAGE_CONTENTS",
                          searchParams: {
                              query: "message: \""+ messageContent + "\"",
                              start: 0, //starting index of the matching record set
                              count: 1 //page size for pagination
                          }
                     };
                     client.search(queryInfo,function(d){
                          var obj = JSON.parse(d["message"]);
                          console.log(obj);
                          if (d["status"] === "success") {
                                  var num2 = obj[0].values.id;
                                  var strnum2 = num2.toString();
                                  arrayForMessage.push(strnum2);
                          }else{
                                 $(canvasDiv).html(gadgetUtil.getCustemText("No content to display","error while creating the error pattern" +
                                 " please try again"));
                          }
                     },function(error){
                          console.log(error);
                          error.message = "Internal server error while data indexing.";
                          onError(error);
                     });
                 }
            }
         }, function (error) {
             console.log(error);
             error.message = "Internal server error while data indexing.";
             onError(error);
         });
    }else{
        $(canvasDiv).html(gadgetUtil.getCustemText("No content to display","there are no error patterns which include this error" +
        " please try another one"));
    }
}, function (error) {
    console.log(error);
    error.message = "Internal server error while data indexing.";
    onError(error);
});
 console.log("------------------");
 for (var j = 0; j < 8; j++) {
    console.log(arrayForClass[j]);//prints undefine
 }
 console.log("------------------");
 console.log(arrayForClass[0]); //prints undefine
 console.log(arrayForClass);//prints corectly
 console.log(arrayForMessage);//printd corectly

}

Answer 1

您的API调用是异步的，这意味着即使您的呼叫未完成，它也会继续工作到下一行。

您获得undefined，因为您对{not 1 yet}变量的console.log引用。 <{1}}此时为空，因此arrayForClass [0]不存在。

下一行你得到正确的结果，因为你arrayForClass到现有的变量，即使它现在是空的，但你的调试工具试图通过在你的数据进入时在控制台中为你更新它来变得聪明

如果你真的想在那一点看到实际值，你需要以某种方式让它变成不可变的，例如：

console.log

这只能解释为什么你在控制台中获取数据的原因。如果你需要使用这些变量，那么必须在每个调用的回调函数中完成。

Java Script数组未定义

1 个答案: