Using eval in Firefox preferences
<p>I' like to change the value of a DOM element according to a user-defined specification. Let's say I want to multiply it by 100. The specification should be defined in FF preferences.</p>

<p>The path of least resistance seems to be to take the value of the element and something like 'action: "*100"' in the preferences and use eval to get the value. However, eval is evil and I believe this is not safe (someone could replace the '*100' with a function etc.).   </p>

<p>So, can you think of some way where I could avoid using eval and still could read the format from the preferences somehow?</p>
