So what if they want 50%? People come looking for scripts and stuff on codecanyon and actually buy... If you choose on not selling on this platform you are just giving away potential sales, customers and a marketing channel. For reference theres hardly any Platform offering you completely free postings in their Marketplace - each and every one of them want their piece of the cake. If it bothers you that much than just double the price (altough i wouldn't advise you to do so) and by all means dont sell on just one platform!!! There are plenty of other platforms which let you sell javascript aswell: exells, buystockscript, marketplace on freelancer, codegrape, marketplace on tutsplus, ...
Another way of selling your javascript:
- Write a quality article in the form of a list - like: 20 of the best Javascript/Jquery slideshows
- In this specific article one or several Slideshow/s would be your very own - linking to decent salespage/s of yours
- And all the other Slideshows would link to ( with refferal links of course ) to your codecanyon (or whatever platform you choose) competitors
- Then make a pressrelease distributing this article on as many related websites as possible