Questions about capability of Javascript
<p>Many years back, I was told that Javascript was harmful, and I remember being annoyed with endless popup when I right-clicked an image to download it.</p>

<p>Now it seems suddenly that Javascript is great, and you can do a lot of things with it to let users have native-like web application experience.</p>

<p>I admit I have missed 6-7 years of Javascript literature, so I hope to start anew with SO kickstarting me to understand the following:</p>

<ol>
<li>Is Javascript mainly concerned about user interface i.e. smoothen interaction between application and users and not about logic processing, number crunching or form processing etc.?</li>
<li>Can Javascript write to local hard drive (besides cookies)?</li>
<li>Can Javascript web application run with Javascript capabilities in browsers turned off? (I would think outright no, but an article on Adaptive Path said 'maybe')</li>
<li>Is AJAX illegal to use due to Eolas patent claim? Is it worth it spending effort learning it when the future is not secure? (I know AJAX is not Javascript)</li>
</ol>

<p>Thanks. Hoping for enlightenment.</p>
