Uncaught ReferenceError: add is not defined in javascript code
<p>I am writing modular javascript code. I wrote a basic calculator with two inputs and four buttons which performs arithmetic operations. When I run my it shows this error in console.</p>

<p><code>Uncaught ReferenceError: add is not defined</code></p>

<p>This happens for all buttons. How can I fix this and why it does not work?</p>

<p>Here is my <strong><a href="http://jsfiddle.net/gmC94/" rel="nofollow">code</a></strong></p>
