Question

我希望每次调用任何其他函数时都调用函数X.我希望尽可能保持通用。

有这两个功能

function x(){ console.log("invoke BEFORE"); }

function someFunction(something){ console.log(something); }

调用someFunction时

someFunction("testoutput");

我希望控制台输出：

>> invoke BEFORE
>> testoutput

我还希望将此行为应用于某个对象的任何函数。

例如：

var myFunctions = {
   first:function(){/* do something */},
   second:function(){/* do something else*/}
}

myFunctions.before（function（）{/ 在 /}之前做一些事情）;

任何人都知道解决方案吗？

编辑：

我想出了这样的解决方案：

Object.prototype.before = function(x){ 
    for(var key in this){
      if(typeof this[key] === "function")
      this[key] = (function(x, f) {
        var g = f;
        return (function() {
            x();
            return g.apply(this, arguments);
        });
      }(x, this[key]));
    }
}

var test = { func: function(){console.log("test")}};

test.before(function(){console.log("before")});

test();

结果：

>> before
>> test

YAAAYYY

你怎么喜欢这个？

Answer 1

这是一个糟糕的主意，可以更加难以理解和调试您的程序。

您可以使用Python中称为“猴子修补”的内容来实现此目的：

(function() {
    {
    var origSomeFunction = someFunction;
    someFunction = (function() {
        x();
        return origSomeFunction.apply(this, arguments);
        });
    }();

这是有效的，因为我更改了（全局）名称someFunction以引用我定义的新函数。在该函数的闭包内，我保留了对要传递调用的原始函数的引用。

Answer 2

在我看来，事件绑定比函数包装更灵活，因为您可以随时删除// Observable var Observable = {}; Observable.create = function (options) { var observable = { events: {} }; var events = options.events || []; var i, l = events.length; for (i = 0; i < l; i++) { observable.events[events[i]] = []; } return observable; }; Observable.one = function (observable, event, handler) { Observable.on(observable, event, function f () { Observable.un(observable, event, f); handler.apply(this, arguments); }); }; Observable.on = function (observable, event, handler) { observable.events[event].push(handler); }; Observable.un = function (observable, event, handler) { observable.events[event].splice( observable.events[event].indexOf(handler), 1 ); }; Observable.emit = function (observable, event, params) { var handlers = observable.events[event]; var i, l = handlers.length; if (!params) params = {}; params.source = observable; for (i = 0; i < l; i++) { handlers[i].call(observable, params); } }; Observable.observeMethod = function (observable, name) { var meth = observable[name]; var before = 'before' + name.toLowerCase(); var after = 'after' + name.toLowerCase(); observable.events[before] = []; observable.events[after] = []; observable[name] = function () { var ret; Observable.emit(observable, before); ret = meth.apply(observable, arguments); Observable.emit(observable, after, { value: ret }); return ret; }; }; // init var printer = init({ sayHello: function () { this.print('Hello World.'); }, sayHi: function (e) { this.print('Hi ' + e.pseudo + '.'); }, print: function (msg) { print(msg); } }); var clock = init({ tid: null, events: ['tick'], stop: function () { clearTimeout(this.tid); }, start: function () { var me = this; var time = 0; clearTimeout(this.tid); (function tick () { me.tid = setTimeout(tick, 1000); me.emit('tick', { time: time++ }); })(); } }); // demo: printer printer.on('afterprint', printNewline); printer.on('beforesayhello', printBullet); printer.sayHello(); printer.sayHello(); printer.un('beforesayhello', printBullet); printer.sayHello(); // demo: clock clock.on('tick', function (e) { if (e.time) printer.print('tick ' + e.time); if (e.time === 3) this.stop(); }); clock.one('afterstop', clock.start); clock.start(); // helpers function init (obj) { obj = initObservable(obj); obj.one = function (event, handler) { Observable.one(this, event, handler); }; obj.on = function (event, handler) { Observable.on(this, event, handler); }; obj.un = function (event, handler) { Observable.un(this, event, handler); }; obj.emit = function (event, params) { Observable.emit(this, event, params); }; return obj; } function initObservable (obj) { var k, observable; observable = Observable.create({ events: obj.events }); for (k in observable) { obj[k] = observable[k]; } for (k in obj) { if (typeof obj[k] === 'function') { Observable.observeMethod(obj, k); } } return obj; } function printBullet () { print('• '); } function printNewline () { print('<br />'); } function print (html) { document.body.innerHTML += html; }。这是一个可能的实现：

onPushReceive

影响Javascript函数调用

2 个答案: