New to javascript

[Liquid Fire]

I right now have a very solid understand of PHP/MySQL/HTML.  I also have a good understanding of CSS and want to further my web development skill by picking up another language.  The best possible language i can find that i don't have a good understanding of is javascript, is there anything else i should learn?  If someone could point me to a site with good javascript tutorials or a good javascript book, that would be great.  I also have a question below:

 

I am make a form library in javascript to have stuff like focusing field, insert values on blur focus and stuff like that and my first function will just make the first field element on focus on page load(or whatever element you specific).  Here is the function:

 

function focus_field(form_name, field_name)

{

    document.form_name.field_name.focus();

}

 

my question is does javascript know that form_name is a variable and not the name of the form, and if so how.  If not how woudl i make a function like this?

[emehrkay]

reference it by id

 

document.getElementById('formfieldid').focus();

 

also, before you dive into js too much, read this post

 

http://blog.mootools.net/2007/6/5/help-i-dont-know-javascript