Which one is most powerful JavaScript or applets and why ?

Answer 1

Personally I'd say JavaScript is more powerful for most type of web apps than Java applets, because:
👉 Java applets may be slow when the user has a slow internet connection, whereas JavaScript apps get downloaded and work on the client-side rather than on the server.
👉 Java applets require browser plugins and security can become a major problem.
👉 Java is compiled into run-time byte code, on the other hand, JavaScript is text based code, you can just upload and run. Nowadays, even CSS and JS are being compressed for transferring over HTTP to improve performance, sending heavy byte code could significantly affect the performance.
👉 JavaScript is web native, super light weight, comes built into the web browser and can offer almost the same performance (if not better) as Java applets.

Answer 2

applets and js are different. applet is used in java to launch a program from browser and this technology is also quiet old now. javascript is a language which is used to define behaviour in webpages. it is interpreted by browser.