s simply a function defined on the <code>actions</code> hash
of a component. Since the action is assigned to an inline handler, the
function definition can define the event object as its first parameter.</p>
<pre class="language-javascript line-numbers"><code class="javascript language-javascript"><span class="token literal-property property">actions</span><span class="token operator">:</span> <span class="token punctuation">{</span>
  <span class="token function">signUp</span><span class="token punctuation