anchor.diff:      Angular only updates the bindings (and therefore the screen)
       if we do something in response to asynchronous events such as keystrokes.
   
  -    That's why we bind the `keyup` event to an expression that does ... well, nothing.
  -    We're binding to the number 0, the shortest expression we can think of.
  +    That's why we bind the `keyup` event to an statement that does ... well, nothing.
  +    We're binding to the number 0, the shortest statement we can think of.
       That is all it takes to keep Angular happy. We said it would be clever!
   :marked
     That local template variable is intriguing. It's clearly easier to get to the textbox with that
  
positive.code:   input box (our design choice).
  
    Although the example *works*, we are rightly wary of JavaScript in HTML.
    Template expressions are powerful. We're supposed to use them responsibly.
    Complex JavaScript in HTML is irresponsible.
  
    Should we reconsider our reluctance to pass the input box into the component?
  
negative.code:   We can use [Angular event bindings](./template-syntax.html#event-binding)
    to respond to [any DOM event](https://developer.mozilla.org/en-US/docs/Web/Events).
  
    The syntax is simple. We surround the DOM event name in parentheses and assign a quoted template statement to it.
    As an example, here's an event binding that implements a click handler:
  +makeExample('user-input/ts/app/click-me.component.ts', 'click-me-button')(format=".", language="html")
  
  <a id="click"></a>
  :marked
    The `(click)` to the left of the equal sign identifies the button's click event as the **target of the binding**.
    The text within quotes on the right is the **template statement** in which we
    respond to the click event by calling the component's `onClickMe` method. A [template statement](./template-syntax.html#template-statements) is a subset
    of JavaScript with restrictions and a few added tricks.
  
    When writing a binding we must be aware of a template statement's **execution context**.
    The identifiers appearing within an statement belong to a specific context object.
    That object is usually the Angular component that controls the template  ... which it definitely is
    in this case because that snippet of HTML belongs to the following component:
  
  