bootstrap：表单必填项*标识，及提交前校验

<script src="{% static ‘js/jquery.min.js‘ %}"></script>
<link href="{% static ‘css/bootstrap.css‘ %}" rel="stylesheet">

{# 前端校验validate   #}
<script src="{% static ‘js/jquery.validate-1.14.0.js‘ %}"></script>
<script src="{% static ‘js/jquery-validation-1.14.0-localization-messages_zh.js‘ %}"></script>

/*必填项前加红色星号*/
.form-group.required .control-label:before {
    color: red;
    content: "*";
    position: absolute;
    margin-left: -15px;
}
/************jQuery.Validate插件样式开始********************/
label.error {
  color: Red;
  padding-left: 0px;
}
input.error {
  border: dashed 1px red;
}
select.error {
  border: dashed 1px red;
}
textarea.error {
  border: dashed 1px red;
}

{# 新增模态框body #}
<form id="add-project">
    <div class="modal-body" style="height: 100%;">
        {# 给class属性增加 required #}
        <div class="form-group required">
            <label for="firstname" class="col-sm-3 control-label">IP</label>
            <div class="col-sm-7">
                {# 增加 required 属性,也可以在下方规则出添加 #}
                <input type="text" class="form-control" id="server_ip" name="server_ip" required
                       placeholder="请输入ip">
            </div>
        </div>

        <div class="form-group required">
            <label for="firstname" class="col-sm-3 control-label">子系统名称</label>
            <div class="col-sm-7">
                <select data-placeholder="选择子系统..." class="form-control" name="sub_sys"
                        id="sub_sys" required="required">
                </select>
            </div>
        </div>
    </div>
</form>

<script type="text/javascript">
    {# 对id="add-project"的表单设置校验规则 #}
    $("#add-project").validate({
        {# 校验规则 #}
        rules: {
            {# 给name属性为server_ip的标签设置规则 #}
            server_ip: {
                required: true, // 设为必填项
                {# 正则表达式校验ip格式 #}
                ip_validate: true  // 增加实时输入校验
            },
            sub_sys: {
                required: true,
                digits: true
            },
        },
        messages: {
            server_ip: "请输入合法的IP",
            sub_sys: "请输入正整数"
        },

        submitHandler: function (form) {
            $(form).ajaxSubmit();
        },

    });
    {# 增加自定义的ip校验 #}
    $.validator.addMethod("ip_validate", function (value, element) {
        let ip_validate = /^((\d)|([1-9]\d)|(1\d{2})|((2[0-4]\d)|(25[0-5])))(\.((\d)|([1-9]\d)|(1\d{2})|((2[0-4]\d)|(25[0-5])))){3}$/;
        return this.optional(element) || (ip_validate.test(value));
    }, "请输入合法的IP");
</script>

function add_project() {
    // 先校验表单在前端是否校验通过
    let flag = $("#add-project").valid();
    if (!flag) {
        //没有通过验证，就不进行下面的ajax提交了
        return;
    }
    {#ajax请求接口#}
    $.ajax({

    })
}