endReactive</h1>
<p>Quite similar to <code>Object.assign</code>, <code>extendReactive</code> takes two arguments, a <code>target</code> object and a <code>properties</code> map, and addes all key-value pairs from the properties to the <code>target</code> as reactive properties.
This is very useful in constructor functions or to extend already reactive objects.</p>
<pre><code class="lang-javascript"><span class="hljs-keyword">var</span> Person = <span class="hljs-function"><span class="hljs-keyword">function