CheckBoxList multi-selection style jquery, C# gets selected items

.checkboxlist label 
{ 
margin-right: 20px; 
}

var label; 
$("#ddlplatform input:checkbox:checked").each(function () { 
label += $(this).next().html(); 
});

<asp:CheckBoxList ID="ddlplatform" runat="server" RepeatDirection="Horizontal" RepeatLayout="Flow" 
CssClass="checkboxlist"> 
<asp:ListItem Value="APP">APP</asp:ListItem> 
<asp:ListItem Value="移动触屏">移动触屏</asp:ListItem> 
<asp:ListItem Value="PC">PC</asp:ListItem> 
<asp:ListItem Value="微信">微信</asp:ListItem> 
<asp:ListItem Value="微博">微博</asp:ListItem> 
</asp:CheckBoxList>

//使用平台 
string Platfrom = string.Empty; 
foreach (ListItem li in this.ddlplatform.Items) 
{ 
if (li.Selected) 
{ 
Platfrom += li.Text + ","; 
} 
} 
Platfrom = Platfrom.TrimEnd(',');