Javascript 回调不是函数NodeJS

我对NodeJS很陌生，但我也很难理解在函数之间传递变量/对象的概念。我感谢任何对我所做错事的帮助

请考虑这个代码：

传入请求：

{ 
    sender: '32165498732165845',
    text: 'shopping',
    originalRequest: 
    { 
        sender: { id: '32165498732165845' },
        recipient: { id: '87971441647898' },
        timestamp: 1488196261509,
        message: { mid: 'mid.1488196261509:c7ccb7f608', seq: 36372, text: 'shopping' } 
    },
    type: 'facebook' 
}

var userId = request.sender;
var listName = request.text;

var listOps = require('./listops/test.js');
listOps.setActive(function (userId, listName, callback) {
    console.log ('Here I expect a callback!');
    return callback; // This will send the message back to user.
});

exports.setActive = function(userId, listName, callback) {
    var message = "User number " + userId + " asks to create a list with name " + listName + ".";
    console.log(userId);
    console.log(listName);
    callback (message);
}

提取相关变量：

{ 
    sender: '32165498732165845',
    text: 'shopping',
    originalRequest: 
    { 
        sender: { id: '32165498732165845' },
        recipient: { id: '87971441647898' },
        timestamp: 1488196261509,
        message: { mid: 'mid.1488196261509:c7ccb7f608', seq: 36372, text: 'shopping' } 
    },
    type: 'facebook' 
}

var userId = request.sender;
var listName = request.text;

var listOps = require('./listops/test.js');
listOps.setActive(function (userId, listName, callback) {
    console.log ('Here I expect a callback!');
    return callback; // This will send the message back to user.
});

exports.setActive = function(userId, listName, callback) {
    var message = "User number " + userId + " asks to create a list with name " + listName + ".";
    console.log(userId);
    console.log(listName);
    callback (message);
}

bot.js:

{ 
    sender: '32165498732165845',
    text: 'shopping',
    originalRequest: 
    { 
        sender: { id: '32165498732165845' },
        recipient: { id: '87971441647898' },
        timestamp: 1488196261509,
        message: { mid: 'mid.1488196261509:c7ccb7f608', seq: 36372, text: 'shopping' } 
    },
    type: 'facebook' 
}

var userId = request.sender;
var listName = request.text;

var listOps = require('./listops/test.js');
listOps.setActive(function (userId, listName, callback) {
    console.log ('Here I expect a callback!');
    return callback; // This will send the message back to user.
});

exports.setActive = function(userId, listName, callback) {
    var message = "User number " + userId + " asks to create a list with name " + listName + ".";
    console.log(userId);
    console.log(listName);
    callback (message);
}

listops/test.js:

{ 
    sender: '32165498732165845',
    text: 'shopping',
    originalRequest: 
    { 
        sender: { id: '32165498732165845' },
        recipient: { id: '87971441647898' },
        timestamp: 1488196261509,
        message: { mid: 'mid.1488196261509:c7ccb7f608', seq: 36372, text: 'shopping' } 
    },
    type: 'facebook' 
}

var userId = request.sender;
var listName = request.text;

var listOps = require('./listops/test.js');
listOps.setActive(function (userId, listName, callback) {
    console.log ('Here I expect a callback!');
    return callback; // This will send the message back to user.
});

exports.setActive = function(userId, listName, callback) {
    var message = "User number " + userId + " asks to create a list with name " + listName + ".";
    console.log(userId);
    console.log(listName);
    callback (message);
}

现在我的问题是，在

listOps.js

中，两个控制台日志的结果都不是我期望的值，它表示

[Function]

和

未定义。因此，我怀疑这是错误消息
[TypeError:callback不是函数]
的根本原因

我正在Lambda中使用Claudia.js。
尝试将您的bot.js更改为以下内容：

var listOps = require('./listops/test.js');

listOps.setActive( userId, listName, function (message) {
      console.log ('message holds the result set in listops/test.js!');
});

如果要在事后处理该消息，只需将其传递给另一个函数：

bot.js：

var listOps = require('./listops/test.js');

var processor = function(userId, listName, message){
     ... process as desired
}

listOps.setActive( userId, listName, function (message) {
      console.log ('message holds the result set in listops/test.js!');
      process(userId, listName, message);
});

发生这种情况是因为在listops/test.js文件中定义了一个函数
exports.setActive=function（userId、listName、callback）
当您在bot.js文件中调用此函数时，它接受三个参数
userId
listName
和
callback
，您只传递一个函数
listOps.setActive（函数（userId、listName、callback）{
这是非法的，正如setActive函数的定义所预期的那样。您需要如下调用此函数

listOps.setActive(userId, listName, function() {
                //your stuffs here
});

您可能想先阅读有关回调的内容，您将
setActive
定义为
函数（userId，listName，callback）
但在bot.js中，您只将匿名函数作为第一个参数传递，如下所示？
listOps.setActive（userId，listName，callback）；if（callback）{console.log（“我期待回调！”）；返回回调；}
看起来很不错，但是…那么回调在哪里呢？回调是listOps.setActive的第三个参数。@DavedeSade第三个参数是一个表达式，在方法调用中回调函数的右边。您可以了解有关函数表达式和函数语句的更多信息。