regarding string expressions..

x=x.replace(/^\s*(.*)/, "$1");

The first argument of the replace function, is a regular expression, that is to be matched against the object string, and replaced by the second argument. The / characters marks the beginning and end of the regular expression, ^ matches the beginning of a string, \s matches any kind of white space character (space, tab and newline), * means that the previous expression (\s in this case) should be repeated any number of times. The ( ) parenthesis encloses a expression and implicitly declares the variable $1 to contain whatever the expression matches. Using multiple ( ) parenthesis in an expression will declare consecutive variables $1, $2, $3 and so on. The contents of the parenthesis (.*) matches any string of charactes. Dot . means any charactes and again * means repeat any number of times.

If you want lean more about this try doing some googeling. Or read the the what the javascript references say about regular expressions http://devedge.netscape.com/library/manuals/2000/javascript/1.5/reference/regexp.html#1193136