js AOP 实现AOP,提供before和after通知

aspect.js

/**
 * js AOP
 * 实现AOP,提供before和after通知
 * @author Leo
 */
!function(global, undefined){
	
	var aspect = function(){};
	
	//aop核心实现
	aspect.core = function (params,advice){
		var source = params.source;
		var method = params.method;
		var exist = source[method];
		
		//上一个fn或原始fn
		var prev = function(){
			return exist.apply(source, arguments);
		};
		
		//当前fn并继承上一个fn
		var curr = advice(params,prev);
		
		//替换原fn
		source[method] = function(){
			return curr ? curr.apply(source, arguments) : prev.apply(source, arguments);
		};
		
		//添加移除通知功能
		return {
			remove: function(){
				curr = null;
				advice = null;
			}
		};
	};
	
	//前置通知实现
	aspect.beforeAdvice = function (params,original){
		return function() {
			var advice = params.advice;
			var isBreak = !!params.isBreak;
			var value = advice(params,arguments);
			
			//是否跳出
			if(isBreak){
				if(value === false){
					return;
				}
				original.apply(this, arguments);
			}else{
				original.apply(this, arguments);
			}
		};
	};
	
	//后置通知实现
	aspect.afterAdvice = function (params,original){
		return function() {
			var value = original.apply(this, arguments);
			var advice = params.advice;
			advice(value);
		};
	};
	
	/**
	 * 前置通知
	 * @param {source,method,advice,isBreak}
	 * @returns function remove
	 */
	aspect.prototype.before = function(params){
		return aspect.core(params,aspect.beforeAdvice);
	};
	
	/**
	 * 后置通知
	 * @param {source,method,advice}
	 * @returns function remove
	 */
	aspect.prototype.after = function(params){
		return aspect.core(params,aspect.afterAdvice);
	};
	
	var aspectFn = new aspect();
	
	//支持amd
	if ( typeof define === "function" && define.amd ) {
		define(function() {
			return aspectFn;
		});
	}else{
		//如果不支持amd 使用对外提供的接口
		global.Aspect = aspectFn;
	}
}(window);