Javascript calling function expression
<p>It makes sense by calling the function this way:</p>

<pre><code>print(square(5));  
function square(n){return n*n}
</code></pre>

<p>But why the following calling doesn't work?</p>

<pre><code>print(square(5));  
square = function (n) {  
  return n * n;  
}  
</code></pre>

<p>What's the solution if we insist to use the format of "square = function (n)"?</p>
