javascript eventemitter多次事件一次

Question

虽然欢迎其他事件库建议,但我正在使用node的eventemitter.

如果触发了几个事件,我想运行一次函数.应该监听多个事件,但如果任何一个事件触发,则会删除所有事件.希望此代码示例演示我正在寻找的内容.

var game = new eventEmitter();
game.once(['player:quit', 'player:disconnect'], function () {
  endGame()
});

处理这个问题的最简洁方法是什么？

注意:需要单独删除绑定函数,因为将绑定其他侦听器.

Answer 1

像这样"扩展"EventEmitter:

var EventEmitter = require('events').EventEmitter;

EventEmitter.prototype.once = function(events, handler){
    // no events, get out!
    if(! events)
        return; 

    // Ugly, but helps getting the rest of the function 
    // short and simple to the eye ... I guess...
    if(!(events instanceof Array))
        events = [events];

    var _this = this;

    var cb = function(){
        events.forEach(function(e){     
            // This only removes the listener itself 
            // from all the events that are listening to it
            // i.e., does not remove other listeners to the same event!
            _this.removeListener(e, cb); 
        });

        // This will allow any args you put in xxx.emit('event', ...) to be sent 
        // to your handler
        handler.apply(_this, Array.prototype.slice.call(arguments, 0));
    };

    events.forEach(function(e){ 
        _this.addListener(e, cb);
    }); 
};

我在这里创建了一个要点:https://gist.github.com/3627823 其中包含一个示例(您的示例,包含一些日志)

[ UPDATE ]以下是对我的实现的修改once,它只删除了注释中所请求的被调用事件:

var EventEmitter = require('events').EventEmitter;

EventEmitter.prototype.once = function(events, handler){
    // no events, get out!
    if(! events)
        return; 

    // Ugly, but helps getting the rest of the function 
    // short and simple to the eye ... I guess...
    if(!(events instanceof Array))
        events = [events];

    var _this = this;

    // A helper function that will generate a handler that 
    // removes itself when its called
    var gen_cb = function(event_name){
        var cb = function(){
            _this.removeListener(event_name, cb);
            // This will allow any args you put in 
            // xxx.emit('event', ...) to be sent 
            // to your handler
            handler.apply(_this, Array.prototype.slice.call(arguments, 0));
        };
        return cb;
    };


    events.forEach(function(e){ 
        _this.addListener(e, gen_cb(e));
    }); 
};

我发现node.js已经once在EventEmitter中有一个方法:在这里查看源代码,但这可能是最近添加的.

Answer 2

像这样的事情怎么样：

var game = new EventEmitter();

var handler = function() {
  game.removeAllListeners('player:quit');
  game.removeAllListeners('player:disconnect');
  endGame();
};

game.on('player:quit', handler);
game.on('player:disconnect', handler);

您可以编写一个包装器on，removeAllListeners以便能够传入数组（例如，循环数组并为每个元素调用onor removeAllListeners）。