通过socket.io发送匿名函数? [英] Sending anonymous functions through socket.io?

问题描述

我想创建一个客户端函数，它可以使用客户端变量接收和执行任意命令.我将从我的服务器发送这些函数，方法是使用 socket.io 发送一个包含匿名函数的 JSON 对象，这将是我的命令.它看起来像下面这样:

I want to create a client-side function that can receive and execute arbitrary commands using client-side variables. I will be sending these functions from my server by using socket.io to send a JSON object containing an anonymous function which will be my command. It looks something like the following:

//client side

socket.on('executecommand', function(data){
    var a = "foo";
    data.execute(a); //should produce "foo"
});

//server side

socket.emit('executecommand', {'execute': function(param){
    console.log(param);
}});

然而，当我尝试时，客户端收到一个空的 json 对象(data == {})，然后抛出异常，因为数据不包含执行方法.这里出了什么问题?

Yet, when I tried it out, the client side received an empty json object (data == {}), then threw an exception because data contained no method execute. What is going wrong here?

推荐答案

JSON 不支持包含 function 定义/表达式.

JSON doesn't support the inclusion of function definitions/expressions.

你可以做的是用你需要的functions定义一个commands对象，然后传递一个commandName:

What you can do instead is to define a commands object with the functions you need and just pass a commandName:

// client-side

var commands = {
    log: function (param) {
        console.log(param);
    }
};

socket.on('executecommand', function(data){
    var a = 'foo';
    commands[data.commandName](a);
});

// server-side

socket.emit('executecommand', { commandName: 'log' });

您也可以使用 fn.apply() 传递参数并检查 commandName 是否与带有 in:

You can also use fn.apply() to pass arguments and check the commandName matches a command with in:

// client-side
var commands = { /* ... */ };

socket.on('executecommand', function(data){
    if (data.commandName in commands) {
        commands[data.commandName].apply(null, data.arguments || []);
    } else {
        console.error('Unrecognized command', data.commandName);
    }
});

// server-side

socket.emit('executecommand', {
    commandName: 'log',
    arguments: [ 'foo' ]
});

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