anchor.diff:    Later in the template we bind the button's `disabled` property to the form's over-all validity via
     the `heroForm` variable. Here's that bit of markup:
   
  -  模板中稍后的部分，通过`heroForm`变量把按钮的`disabled`属性绑定到表单的整体有效性。这里是那点HTML：
  +  模板中稍后的部分，通过`heroForm`变量把按钮的`disabled`属性绑定到表单的整体有效性。这里是那点 HTML：
   
   +makeExample('forms/ts/app/hero-form.component.html', 'submit-button')
   :marked
  
positive.code: 
    1. Handle form submission with **ngSubmit**
  
       使用**ngSubmit**处理表单提交
  
    1. Disable the form’s submit button until the form is valid
  
  
negative.code: 
    Here's how we do it for the *name* input box:
  
    对 *Name* 输入框做如下修改：
  +makeExample('forms/ts/app/hero-form.component.html',
    'name-with-error-msg',
    'app/hero-form.component.html (节选)')(format=".")
  