关于serialize() FormData serializeArray()表单序列化

<form class="form-horizontal" role="form">
        <div class="form-group">
            <label for="firstname" class="col-sm-2 control-label">名字</label>
            <div class="col-sm-10">
                <input type="text" name=‘firstname‘ class="form-control" id="firstname" 
                       placeholder="请输入名字">
            </div>
        </div>
        <div class="form-group">
            <label for="lastname" class="col-sm-2 control-label">姓</label>
            <div class="col-sm-10">
                <input type="text" name="lastname" class="form-control" id="lastname" 
                       placeholder="请输入姓">
            </div>
        </div>
        
        <div class="form-group">
            <div class="col-sm-offset-2 col-sm-10">
                <button type="button" class="btn btn-default">登录</button>
            </div>
        </div>
    </form>

$(‘.btn-default‘).click(function () {
            var formData = new FormData();
            formData.append("firstname", $(‘#firstname‘).val());
            formData.append("lastname", $(‘#lastname‘).val());

            $.ajax({
                headers: {
                    Accept: "application/json; charset=utf-8"//设置headers里的accept
                },
                type: ‘POST‘,
                data: formData,
                url: ‘wwww‘,
                processData: false,
                contentType: false,
                async: false,
                success: function (data) {
                    if (typeof (data) == undefined) {
                        alert("用户信息已丢失，请重新登录！");
                    }
                    if (data.ErrorMsg == "") {
                        alert(‘美文发布成功！‘);
                    } else { 
                        alert(data.ErrorMsg); 
                    }
                }
            });

        });

$(‘.btn-default‘).click(function () {

           var formData=$("form").serialize();//序列化表单
            $.ajax({
                headers: {
                    Accept: "application/json; charset=utf-8"//设置headers里的accept
                },
                type: ‘POST‘,
                data: formData,
                url: ‘wwww‘,
                processData: false,
                contentType: false,
                async: false,
                success: function (data) {
                    if (typeof (data) == undefined) {
                        alert("用户信息已丢失，请重新登录！");
                    }
                    if (data.ErrorMsg == "") {
                        alert(‘美文发布成功！‘);
                    } else { 
                        alert(data.ErrorMsg); 
                    }
                }
            });

        });

$(‘.btn-default‘).click(function () {

           var formData=$("form").serializeArray();//序列化表单json
           console.log(formData);//打印出数据
            $.ajax({
                headers: {
                    Accept: "application/json; charset=utf-8"//设置headers里的accept
                },
                type: ‘POST‘,
                data: formData,
                url: ‘wwww‘,
                processData: false,
                contentType: false,
                async: false,
                success: function (data) {
                    if (typeof (data) == undefined) {
                        alert("用户信息已丢失，请重新登录！");
                    }
                    if (data.ErrorMsg == "") {
                        alert(‘美文发布成功！‘);
                    } else { 
                        alert(data.ErrorMsg); 
                    }
                }
            });

        });