实现Observer模式（转载）

http://blog.csdn.net/kentchenj/archive/2007/02/08/1505429.aspx  (转载)

< html > < head > < meta http - equiv = " Content-Type "  content = " text/html; charset=GB2312 "   /> < title > 实现Observer模式. </ title > < script language = JavaScript >            function  Observer()  ... {            this.fns = [];          }           Observer.prototype  =   ... {            subscribe : function(fn) ...{                this.fns.push(fn);            },            unsubscribe : function(fn) ...{                this.fns = this.fns.filter(                    function(el) ...{                        if ( el !== fn ) ...{                            return el;                        }                    }                );          },          fire : function(o, thisObj) ...{                var scope = thisObj || window;                this.fns.forEach(                    function(el) ...{                                    //相当于：window.fn1(参数)  其中，参数是o.fire('xyz')中的xyz，转移成fn1和fn2执行了.                        el.call(scope, o);                    }                );          }        } ;                 var  o  =   new  Observer;         var  fn1  =   function (p)  ... {            alert("fn1 " + p);        } ;         var  fn2  =   function (p)  ... {            alert("fn2 " + p);        } ;        o.subscribe(fn1);        o.subscribe(fn2);                o.fire( ' xyz ' ); </ script >   </ head > < body > </ body >