Q:

Reading a javascript script, why so many $ (dollar signs)? 

I am trying to decipher a .js script and I am finding it filled with $ throughout?   Is there any reason to use this?   I'm pretty new to JavaScript. 

A:

I think you are reading a JavaScript library famously known as jQuery (or possibly another library).  The $ is just a short form for a namespace or use as an identifier.  
You can think of it like this jQuery('p') to select all the paragraphs on a page, 
or for short form you can just write $('p'). 
Here is a link for jQuery tutorials/docs jQuery
Here is a list of standards section 7.6 describes it in detail ECMA Standard

A:

A number of libraries have used $ as their primary symbol.  It's nothing to do with JavaScript per se, but it's a short distinctive symbol and so libraries have tended to glom onto it. ( You can start an identifier with $ in JavaScript, and identifiers can be one character long, so $ is a valid identifier, just like a or x.)
I know of at least three libraries that use $ for something:

jQuery - It's the all purpose function for jQuery, an alias of the jQuery function; more here. 
Prototype - It's Prototype's replacement for document.getElementById, more here.  Prototype also has $$, which is for looking things up via CSS selectors. 
MooTools - Same use as Prototype (because MooTools is either "inspired by" or "forked from" Prototype, some years back, depending on who you ask), more here.  And like Prototype, it has $$. 

A:

$ is a variable.   A number of frameworks use it as a short hand for using it.   Prototype and Jquery are the two big ones.   This does not mean that the $ automatically is either one of those.   It could be anything as anything in JavaScript can assign something to the $.   This is something to be aware of, because when you start combining scripts from different sources, it's really easy for one to accidentally reassign a variable to something else.  
Most likely it is a framework reference, but you'll have to read the code to be sure.   At one point in time the $ was meant to be used to indicate that the code referenced by it was auto generated, but this is just a guideline. 