.disno{display: none }
.disbl{display:block;}
document.onmousedown=function(event){
var e=event ||window.event;
var elm=e.srcElement || e.target;
if(elm.id!="showcar"){
$("#morecar").attr('className', 'disno');
}
}
<a href="#" id="showcar">广州网站建设</a>
<div class="'disbl'" id="morecar">广州网站建设</div>