select 默认占位符的写法

//获取单位类型/单位性质/行业编码/诚信等级
function getUnitType(htmlId,param,placeholder){
$.ajax({
url : "detail/getcode",
type : "GET",
dataType :"json",
data:{
"param":param
},
async:false,
success : function(data){
var html = '<option value="" disabled selected style="display:none">'+placeholder+'</option>';
for (var i = 0; i < data.length; i++) {
var item = data[i];
html = html + "<option value='"+ item.id+ "'>"+ item.value+ "</option>";
}
$("#"+htmlId).html(html);
}
});
}

$(").select2();