jquery的意外烦恼

html

<div id="PersonalInfoLeft" >
                                    <div id="P0" class="eeedss1">
                                        <span class="Icocss">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span>
                                        <div >
                                            <span class="TextLeftcss">合同</span>
                                        </div>
                                    </div>
                                    <div id="P1" class="eeedss1">
                                        <span class="Icocss">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span>
                                        <div >
                                            <span class="TextLeftcss">任务书</span>
                                        </div>
                                    </div>
                                    <div id="P2" class="eeedss1" style="margin-bottom:0px;">
                                        <div>
                                            <span class="Icocss">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span>
                                            <span class="TextLeftcss" >工作大纲</span>
                                        </div>
                                    </div>                                    
                                    <div id="P3" class="eeedss1">
                                        <span class="Icocss">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span>
                                        <div>
                                            <span class="TextLeftcss">设计</span>
                                        </div>
                                    </div>
   </div>

　　js jquery

$("#PersonalInfoLeft").children("div").eq(0).attr("class","eeedss");这个有效
$("div[id^='P']").eq(0).attr("class","eeedss");这个就乱套了

$("div[id^='P':eq(0)]").attr("class","eeedss");//也是乱套的

但是

$("div[id^='P']").hide();  这个是OK的

　　

神马原因呢 先搁着  有时间去查查 干项目去了