Why does the JavaScript need to start with “;”?

I would say since scripts are often concatenated and minified/compressed/sent together there’s a chance the last guy had something like:

return {
   'var':'value'
}

at the end of the last script without a ; on the end. If you have a ; at the start on yours, it’s safe, example:

return {
   'var':'value'
}
;(function( $ ){ //Safe (still, screw you, last guy!)

return {
   'var':'value'
}
(function( $ ){ //Oh crap, closure open, kaboom!

return {
   'var':'value'
};
;(function( $ ){ //Extra ;, still safe, no harm