Want to create modern Web applications? You'll need to use JavaScript. But don't write the JavaScript yourself; use one of the high-quality open-source libraries that let you concentrate on your coding, rather than browser incompatibilities.
Back in 1995, while I was working for Time Warner's Web division, someone showed me the latest technology advance to come out of Netscape, then the hottest company. It was a language called LiveScript, and it was a programming language that worked within the browser.