js ajax异步访问,jquery的each方法

$.ajax({

cache: true,
type: "POST",
url:"******.do",
data:{typename:typename},
async: false,
error: function(request) {
alert("连接异常,请联系管理员");
},
success: function(data) {
$.each(data.BData,function(i,item){
str_html += '<option>'+item.name+'</option>'
})

}
});