调试易

function fun_blur()
{
document.getElementById("divcity").style.display="none";
}
<div id="divcity" class="city" style="display:none;" tabIndex="0" onblur="fun_blur()">
             <ul class="city_top">
                 <li><a href="#" title="hot" onclick="fun_select(this)">热门</a></li>
                 <li><a href="#" title="ABCD" onclick="fun_select(this)">ABCD</a></li>
                 <li><a href="#" title="EFGH" onclick="fun_select(this)">EFGH</a></li>
                 <li><a href="#" title="JKLM" onclick="fun_select(this)">JKLM</a></li>
                 <li><a href="#" title="NOPQRS" onclick="fun_select(this)">NOPQRS</a></li>
                 <li><a href="#" title="YZ" onclick="fun_select(this)">YZ</a></li>
                </ul></div>div全部发完，后面基本一样的。这里的点击是切换分组的。但点了DIV也直接隐藏了

DIV没全部发完。。少打了个“没”字

想把代码全上，字符不够，就留了ABCD一页。     <div>
         <input type="text" id="city"  onclick="fun_cityclick()" />
            <div id="divcity" class="city" style="display:none;" tabIndex="0" onblur="fun_blur()">
             <ul class="city_top">
                 <li><a href="#" title="hot" onclick="fun_select(this)">热门</a></li>
                 <li><a href="#" title="ABCD" onclick="fun_select(this)">ABCD</a></li>
                 <li><a href="#" title="EFGH" onclick="fun_select(this)">EFGH</a></li>
                 <li><a href="#" title="JKLM" onclick="fun_select(this)">JKLM</a></li>
                 <li><a href="#" title="NOPQRS" onclick="fun_select(this)">NOPQRS</a></li>
                 <li><a href="#" title="YZ" onclick="fun_select(this)">YZ</a></li>
                </ul>
                <div id="hot">
                 <ul class="city_list">
                     <li>
                         <a href="#" onclick="fun_city(this)">北京</a>
                         <a href="#" onclick="fun_city(this)">上海</a>
                         <a href="#" onclick="fun_city(this)">天津</a>
                         <a href="#" onclick="fun_city(this)">重庆</a>
                         <a href="#" onclick="fun_city(this)">大连</a>
                         <a href="#" onclick="fun_city(this)">青岛</a>
                     </li>
                     <li>
                         <a href="#" onclick="fun_city(this)">西安</a>
                         <a href="#" onclick="fun_city(this)">南京</a>
                         <a href="#" onclick="fun_city(this)">苏州</a>
                         <a href="#" onclick="fun_city(this)">杭州</a>
                         <a href="#" onclick="fun_city(this)">厦门</a>
                         <a href="#" onclick="fun_city(this)">成都</a>
                     </li>
                     <li>
                         <a href="#" onclick="fun_city(this)">深圳</a>
                         <a href="#" onclick="fun_city(this)">广州</a>
                         <a href="#" onclick="fun_city(this)">三亚</a>
                         <a href="#" onclick="fun_city(this)">台北</a>
                         <a href="#" onclick="fun_city(this)">香港</a>
                         <a href="#" onclick="fun_city(this)">济南</a>
                     </li>
                     <li>
                         <a href="#" onclick="fun_city(this)">宁波</a>
                         <a href="#" onclick="fun_city(this)">沈阳</a>
                         <a href="#" onclick="fun_city(this)">武汉</a>
                     </li>
                    </ul>
                </div>
                <div id="ABCD" style="display:none;">
                 <ul class="city_list">
                     <li>
                         <a href="#" onclick="fun_city(this)">阿坝</a>
                         <a href="#" onclick="fun_city(this)">阿克苏</a>
                         <a href="#" onclick="fun_city(this)">阿拉善</a>
                         <a href="#" onclick="fun_city(this)">阿勒泰</a>
                         <a href="#" onclick="fun_city(this)">阿里</a>
                         <a href="#" onclick="fun_city(this)">安康</a>
                     </li>
                     <li>
                         <a href="#" onclick="fun_city(this)">安庆</a>
                         <a href="#" onclick="fun_city(this)">鞍山</a>
                         <a href="#" onclick="fun_city(this)">安顺</a>
                         <a href="#" onclick="fun_city(this)">安阳</a>
                         <a href="#" onclick="fun_city(this)">澳门</a>
                     </li>
                     <li>
                         <a href="#" onclick="fun_city(this)">白城</a>
                         <a href="#" onclick="fun_city(this)">百色</a>
                         <a href="#" onclick="fun_city(this)">白沙</a>
                         <a href="#" onclick="fun_city(this)">白山</a>
                         <a href="#" onclick="fun_city(this)">白银</a>
                         <a href="#" onclick="fun_city(this)">保定</a>
                     </li>
                     <li>
                         <a href="#" onclick="fun_city(this)">宝鸡</a>
                         <a href="#" onclick="fun_city(this)">保山</a>
                         <a href="#" onclick="fun_city(this)">保亭</a>
                         <a href="#" onclick="fun_city(this)">包山</a>
                         <a href="#" onclick="fun_city(this)">巴彦淖尔</a>
                         <a href="#" onclick="fun_city(this)">巴中</a>
                     </li>
                    </ul>
                </div>
                
                </div>
            </div>
        </div>
// JavaScript Document
function fun_city(var_a)
{
document.getElementById("city").value=var_a.innerHTML;
document.getElementById("divcity").style.display="block";
document.getElementById("divcity").style.display="none";
}
function fun_cityclick()
{
document.getElementById("divcity").style.display="block";
document.getElementById("divcity").focus();
}
function fun_select(var_city)
{
document.getElementById("hot").style.display="none";
document.getElementById("ABCD").style.display="none";
document.getElementById("EFGH").style.display="none";
document.getElementById("JKLM").style.display="none";
document.getElementById("NOPQRS").style.display="none";
document.getElementById("YZ").style.display="none";
document.getElementById(var_city.title).style.display="block";
}
function fun_blur()
{
document.getElementById("divcity").style.display="none";
}

你使用mouseover吧，具体是mouseover还是mouseup搞忘了

总之这两个事件是有点点区别的，一个是鼠标在这个元素区域内不包括其子元素，另一个事件是鼠标在这个元素内包含它的子元素。这两个事件可以使用jquery的事件处理

我想做的是一个隐藏DIV选择城市，然后当鼠标点击那个DIV以外时，隐藏DIV，当点击的是DIV里面的A标签时，也隐藏DIV，但把A标签的内容赋给文本框。遇到的问题是我设的DIV失去焦点时隐藏，现在至少我认为当点击DIV里面的A标签，他也调用了失去焦点的事件，而且文本框的值没改变