Switching out an object's prototype
<p>I'm trying to understand how prototypes work. Why does the following break?</p>

<pre><code>var A = function A(){this.a = 0},
    aa = new A;

A.prototype = {hi:"hello"};

aa.constructor.prototype //-&gt;{hi:"hello"} ok so far :)

aa.hi //undefined?? why? :(
</code></pre>

<p>Thanks in advance!</p>
