Currently Java script become more popular, You can use it into menu bar and image slider, jQuery use to controlling a list of items in horizontal or vertical order, you can add rating feature in your website. Hence there are several part in website where you can Java script or jquery to make it more attractive and user friendly.
While JS is indeed growing in popularity, keep in mind that it will slow down the overall load time of your web page, which affects both bounce rate and website popularity.
One of the responsibilities of my job is managing the company website. Weekly, I review the site's stats and determine such things as page load time, website traffic, bounce rate and the like. When there is a increase in bounce rate or load time, I have to determine why. If daily page views (which average around 30k) go down, I have to find the problem and fix it. Almost everytime, the problem has to do with slower than usual page load time. Typically, a web page that takes longer than 3 seconds to load will lose traffic. Slow load time results in higher bounce rate, which for an online business can be very bad.
PERVEIVED load time is far more important than actual download time. If it were not then there would be no point in ajax scripts that continue adding to the bottom of the current page where the actual download time for the page is theoretically infinite.
Perceived load time and actual load time, for all practical purposes, are the same thing. Just because the page may be VISIBLE does not make usability pleasant or quick. Anyone who's ever gone to a website that takes 15 seconds to finish downloading content knows exactly what I'm talking about. The functionality of the page is drastically affected and things like even scrolling down the page can be very frustrating.
When Facebook first started adding all their on-page apps, many people had problems with the site. While visibility may not have been affected, their ability to actually interact with the page was stifled and as people stopped using Facebook, they were forced to address the issue. With better software and app development standards, Facebook was able to generate quicker load time on their site, improving usability and popularity.
The bottom line is this, the more scripts that are added to a web page, regardless where they are placed, the more unpleasant visitor experience will be.
HEy try to use compressed java scripts in web page coding, because more coding makes web page heavy.