js判断回车，区分IE，火狐，谷歌

if(document.addEventListener){//如果是Firefox 
            document.addEventListener("keypress",fireFoxHandler, true); 
        }else{ 
            document.attachEvent("onkeypress",ieHandler); 
        } 
        function fireFoxHandler(evt){ 
            if(evt.keyCode==13){ 
                com_search(); 
            } 
        } 
        function ieHandler(evt){ 
            if(evt.keyCode==13){ 
                com_search(); 
            } 
        }