jquery实现触发、失去焦点操作并执行ajax操作

js---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

// 失去焦点

$("#login_username").blur(function() {

var login_username = $("#login_username").val();

//ajax

$.ajax({
url : rootUrl + "/user/vtloginname",
data : {
loginname : login_username
},
success : function(result) {
if (!result.success) {
valid = false;
showError(login_userNameError, '*' + result.msg);
}
}
});

});

//获得焦点

$("#login_username").focus(function() {
hideError(login_userNameError);
});

//显示与隐藏

function showError(jqId, msg) {
$(jqId).html(msg);
$(jqId).show();
}


// 隐藏错误信息
function hideError(jqId) {
$(jqId).hide();
}

jsp中---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

<div class="form-group">
<label for="login_username" class="col-sm-3 control-label">登录账号</label>
<div class="col-sm-9">
<input type="text" id="login_username" class="form-control"
name="loginname" placeholder="登录账号">
<span id="login_userNameError" style="color:red;display:none" class="error"></span>
</div>
</div>