layui怎么赋值和获取form表单

<form class="layui-form" action="" lay-filter='testForm'>
  <div class="layui-form-item">
    <label class="layui-form-label">账号</label>
    <div class="layui-input-block">
      <input type="text" name="username" class="layui-input">
    </div>
  </div>
  <div class="layui-form-item">
    <label class="layui-form-label">密码框</label>
    <div class="layui-input-inline">
      <input type="password" name="pass" class="layui-input">
    </div>
  </div>
</form>

let data = layui.form.val(`testForm`);
console.log(" ~ file: widget.js ~ line 209 ~ data", data);

layui.form.val("testForm", { 
  "username": "lele" 
  ,"pass": "123456"
});