《深入浅出node.js》 P77 学习

///用于处理多个事件对应一个侦听器的情况 var count = 0;var results = {};var done = function (key, value){    results[key] = value;    count++;    if (count === 3){        ///渲染页面        render(results);    }};fs.readFile(template_path, "utf8", function(err, template){    done("template", template);});db.query(sql, function(err, data){    done("data", data);});lion.get(funciton (err, resources){    done("resources", resources);});///2015-10-14 11:05:49///使用偏函数来处理哨兵变量和第三方函数的关系var after = function (times, callback) {    var count = 0, results = {};    return function (key, value){        results[key] = value;        count++;        if (count === times) {            callback(results);        }    };};var done = after(times, render);///事实上这是在对done作初始化，同时初始化的还有done的属性count, results///如果再用after初始化另外一个函数，则二者之间的count和results互不相干。done = function (key, value){    results[key] = value;    count++;    if (count === times) {        callback(results);    }}emitter.on("done", done);///事实上是emitter.on("done", function(key, value){    results[key] = value;    count++;    if (count === times) {        callback(results);    }})emitter.emit("done", "template", template);///监听到事件之后，运行的函数变成：emitter.on("done", function("template", template){    functionbody;})