Node js - 因为没有回调函数而返回错误

Posted 2023-02-19

【中文标题】Node js - 因为没有回调函数而返回错误

【英文标题】：Node js - error returned because no callback function

【发布时间】：2018-06-30 12:08:26

【问题描述】：

我有以下节点 js 脚本，它返回作业的持续时间：

var http = require("http");
var fs = require('fs');
var async = require('async');
var readline = require('readline')
//var db = require('./dbPool');

//get file name
var options =  
    "method" : "GET",
    "hostname" : "127.0.0.1",
    "port" : "18080",
    "path" : "/api/v1/applications/"
;

exports.getId = function (callback) 
    var req = http.request(options, function (res) 

        var chunks = [];

        res.on("data", function (chunk) 
            chunks.push(chunk);
        );

        res.on("end", function () 
            var body = JSON.parse(Buffer.concat(chunks));

            var arrFound = Object.keys(body).filter(function(key) 
                if (body[key].name.indexOf("TeraGen (5MB)") > -1) 
                    return body[key].name;
                
            ).reduce(function(obj, key)
                obj = body[key].id;
                return obj;
            , );;
            callback(null, arrFound);
        );
    );
    req.end();


exports.getId(function(err, id)

    //get file name
    var options =  
        "method" : "GET",
        "hostname" : "127.0.0.1",
        "port" : "18080",
        "path" : "/api/v1/applications/" + id
    ;

    var req = http.request(options, function (res) 

        var chunks = [];

        res.on("data", function (chunk) 
            chunks.push(chunk);
        );

        res.on("end", function () 
            var body = JSON.parse(Buffer.concat(chunks));

            var attempts = body.attempts

            var arrFound = Object.keys(body).filter(function(key) 

                    return attempts[0].duration;

            ).reduce(function(obj, key)
                obj = body.attempts[0].duration;
                return obj;
            , );
            //console.log(arrFound);
            callback(null, arrFound);
        );
    );
    req.end();
);

当我运行它时，会抛出以下错误：

$ 节点 getEventLog.js 815963 /modules/getEventLog.js:73 回调（空，arrFound）； ^

ReferenceError: 未定义回调 在传入消息。 (/modules/getEventLog.js:73:13) 在 emitNone (events.js:111:20) 在 IncomingMessage.emit (events.js:208:7) 在 endReadableNT (_stream_readable.js:1056:12) 在 _combinedTickCallback (内部/进程/next_tick.js:138:11) 在 process._tickCallback (internal/process/next_tick.js:180:9)

我觉得我需要创建一个函数，所以我尝试了：

exports.getDuration = function (callback) 
    exports.getId(function(err, id)

    //get file name
    var options =  
        "method" : "GET",
        "hostname" : "127.0.0.1",
        "port" : "18080",
        "path" : "/api/v1/applications/" + id
    ;

    var req = http.request(options, function (res) 

        var chunks = [];

        res.on("data", function (chunk) 
            chunks.push(chunk);
        );

        res.on("end", function () 
            var body = JSON.parse(Buffer.concat(chunks));

            var attempts = body.attempts

            var arrFound = Object.keys(body).filter(function(key) 

                    return attempts[0].duration;

            ).reduce(function(obj, key)
                obj = body.attempts[0].duration;
                return obj;
            , );
            console.log(arrFound);
            callback(null, arrFound);
        );
    );
    req.end();
    )
;

但它似乎不起作用。我哪里错了？

【参考方案1】：

你的第二个例子应该可以工作，你只需要调用它

exports.getDuration(function(err, duration)
      if(err) return console.log(err)
      console.log(duration)

您的第一个示例不起作用，因为您正在尝试回调数据但尚未指定回调。如果您不想像第二个示例那样创建另一个函数，只需删除回调并使用持续时间数据做任何您需要的事情

 //console.log(arrFound);
 callback(null, arrFound); //remove this

 //arrFound should be the duration, so do whatever you need with it here