JQuery autocomplete获得焦点触发弹出下拉框

需求：autocomplete控件，当点击获得焦点的时候也要弹出下拉列表（autocomplete默认是输入之后才会跟随出下拉列表），下面直接贴代码。

js代码：

$("#customerName").autocomplete({
minLength: 0,
source: function (request, response) {
var customerName = $("#customerName").val();
$.ajax({
url: "/api/pmstransaction/getcustomerinfo",
dataType: "json",
data: {
customerName: customerName
},
success: function (data) {
response(data.Data);
}
});
},
focus: function (event, ui) {
$("#customerName").val(ui.item.CustomerName);
return false;
},
select: function (event, ui) {
module.viewModel.customerInfo.CustomerName(ui.item.CustomerName);
module.viewModel.customerInfo.CustomerTaxCode(ui.item.CustomerTaxCode);
module.viewModel.customerInfo.CustomerAddressPhone(ui.item.CustomerAddressPhone);
module.viewModel.customerInfo.CustomerBankAccount(ui.item.CustomerBankAccount);
return false;
}
}).focus(function () {
$(this).autocomplete("search");
}).autocomplete("instance")._renderItem = function (ul, item) {
return $("<li>")
.append("<div>" + item.CustomerName + "</div>")
.appendTo(ul);
}

　　

　　重点代码

focus(function () {
$(this).autocomplete("search");
})