Angular 2.0.0-beta.17 breaking changes

Angular 2 更該至 beta.17 後，發生 warning：
Template parse warnings：

"#" inside of expressions is deprecated. Use "Let" instead! ....

似乎有做小改版，趕緊來看看 release note ，內容如下：

Before:

• Outside of ngFor, a #... meant a reference.
• Inside of ngFor, it meant a local variable.

This was pattern was confusing.

After:

• <template #abc> now defines a reference to a TemplateRef, instead of an input variable used inside of the template.
• Inside of structural directives that declare local variables, such as *ngFor, usage of #... is deprecated. Use let instead.
  • <div *ngFor="#item of items"> now becomes <div *ngFor="let item of items">
• var-... is deprecated.
  • use # or a ref- outside of *ngFor
  • for ngFor, use the syntax: <template ngFor let-... [ngForOf]="...">

簡單說 ＃ 的用法會讓人混淆，
搭配 ngFor 使用，是定義迴圈內的私有變數，
但放在 dom element attribute 位置時，指的又是此 dom element 的參考，

為避免混淆，所以 ngFor 改用 let 宣告私有變數，
就是這麼一回事，
了解前因後果後，
就不會想要翻桌，
狂罵改個屁呀！