Object # has no method 'foo' 这个错误时什么意思?

[昵称90天可以改一次]

调用方

var Net = require('net')
//var ProtoBuf = require("protobufjs");

var ServerSock = require('./SvrSocket');

var server = Net.createServer( onConnected );

server.listen(20660, function() {
	console.log(' server  running...');

});

function onConnected( socket ){

	console.log('connected..');
	
	var serverSocket = ServerSock.createSvrSocket(null);
	
	serverSocket.setSocket( socket );
	
} 

然后SvrSocket是这个对象

module.exports = 
{	
	createSvrSocket : function( socket)
	{		
		return new SvrSocket(socket);
	},
}


function SvrSocket( socket )
{
	this.m_Socket = socket;
	
	
}

SvrSocket.prototype.onData = function( buffer )
{
	//this.foo();
}

SvrSocket.prototype.setSocket = function( socket ) {
	this.m_Socket = socket;
	
	this.m_Socket.on('data', this.onData );	
	
	this.foo();
}	

SvrSocket.prototype.foo = function() {

}

这么做的话 就没有错误

但是如果我改成这样

module.exports = 
{	
	createSvrSocket : function( socket)
	{		
		return new SvrSocket(socket);
	},
}


function SvrSocket( socket )
{
	this.m_Socket = socket;
	
	
}

SvrSocket.prototype.onData = function( buffer )
{
	this.foo();	
}

SvrSocket.prototype.setSocket = function( socket ) {
	this.m_Socket = socket;
	
	this.m_Socket.on('data', this.onData );	
	
	//this.foo();
}	

SvrSocket.prototype.foo = function() {

}

当socket收到消息的时候就会提示这个错
this.foo();
^
TypeError: Object #<Socket> has no method 'foo'

[潮起潮落]

你看一下两个地方的this是否一样

[昵称90天可以改一次]

谢谢, 我明白了. .javascript的this是和其他OOB语言不太一样