做一个聊天页面，ajax异步请求数据时，不论有无数据返回，ios都会闪动一下，而android不会闪动 ，这是怎么回事，该如何解决
$(document).ready(function(){
$('.loading_box').attr('style','display:none');
ajaxform();
window.setInterval("ajaxform()",3000);
});
function ajaxform(){
var id=$(".main_box ul li:last-child").find('.delete_btn').attr('field');//alert(id);
$.post(
"{:U('App/Friends/ajaxform')}",
{"openid":openid,"id":id},
function(data){
if (data) {
var str = "";console.log(data);
$.each(data, function(index, array) {
if(array['openid']==openid){
if(array['type']==0){
//普通文字或图片
str='<li class="chart-right"><p class="chart_text_box"><p class="jieshao"><p>'+array['uname']+'</p><p>'+array['time']+'</p></p><p class="chart_text_qipao_right"><p>'+array['content']+'</p></p><p class="operation_box"><p class="delete_btn" field="'+array['id']+'">删除</p></p></p><p class="persion_img_right"><img src="'+array['headimgurl']+'"><font><img src="{$tpl}App/Friends/Public/img/vipv'+array['classid']+'l.png"></font></p></li>';
}else{
//我的霸屏
str='<li class="chart-right"><p class="chart_text_box"><p class="jieshao"><p>'+array['uname']+'</p><p>'+array['time']+'</p></p><p class="chart_text_qipao_right"><p><i class="money_text">重金霸屏'+arr[array['type']]+'秒</i>'+array['content'];
if(array['img']!=""){
str+='<font class="chart_img"><img src="'+array['img']+'"></font>';
}
str+='</p></p><p class="operation_box"><p class="delete_btn" field="'+array['id']+'">删除</p></p></p> <p class="persion_img_right"><img src="'+array['headimgurl']+'"><font><img src="{$tpl}App/Friends/Public/img/vipv'+array['classid']+'l.png"></font></p> </li>';
}
}else{
if(array['type']==0){
//普通文字或图片
str = ' <li class="chart-left"><p class="persion_img_left"><img src="'+array['headimgurl']+'"><font><img src="{$tpl}App/Friends/Public/img/vipv'+array['classid']+'l.png"></font></p> <p class="chart_text_box"><p class="jieshao"><p>'+array['uname']+'</p><p>'+array['time']+'</p></p><p class="chart_text_qipao_left"><span class="sanjiao_left"></span><p>'+array["content"]+'</p></p>';
if(isadmin){
str+='<p class="operation_box"><p class="delete_btn" field="'+array['id']+'">删除</p> <p class="blacklist" field="'+array['openid']+'">拉黑</p></p>';
}
str+='</p> </li>';
}else{
//他人霸屏
str='<li class="chart-left "><p class="persion_img_left"><img src="'+array['headimgurl']+'"><font><img src="{$tpl}App/Friends/Public/img/vipv'+array['classid']+'l.png"></font></p> <p class="chart_text_box"><p class="jieshao"><p>'+array['uname']+'</p><p>'+array['time']+'</p></p><p class="chart_text_qipao_left"><span class="sanjiao_left"></span><p><i class="money_text">重金霸屏'+arr[array['type']]+'秒</i>'+array['content'];
if(array['img']!=""){
str+='<font class="chart_img"><img src="'+array['img']+'"></font>';
}
str+='</p></p>';
if(isadmin){
str+='<p class="operation_box"><p class="delete_btn" field="'+array['id']+'">删除</p> <p class="blacklist" field="'+array['openid']+'">拉黑</p></p>';
}
str+='</p> </li>';
}
}
$(".main_box ul").append(str);
$('.main_box').scrollTop( $('.main_box')[0].scrollHeight );
});
}
}
);
}
