There are thousands of JavaScripts freely available for downloading. These range from Drop Down menus to Snow Effects, from Mouse-over Effects to Digital Real-Time Clocks.
JavaScript is useful for introducing limited animation to your web pages without the download times associated with Flash animations. Your page tracking and Google Adsense tracking also use JavaScript.
People see JavaScript programming as a new and highly paid career. Universities supply the courses because the demand is there and it’s a good way for the university to make money. As these qualified programmers come onto the jobs market, the number of programmers is going to exceed the number of vacancies and salaries will fall.
When companies can outsource their programming needs to low cost countries like India and China, they are unlikely to want very many highly paid programmers on their rolls.
If you do learn JavaScript you can earn money on one of the freelancing sites, by bidding on various projects. Be aware that you will not be able to compete on price with programmers from India or China, to compete on quality and completion times. The reputation you establish early on will stay with you for a long time, so make sure it is an impeccable one.
JavaScript does have some disadvantages. It works differently on different browsers and it increases the download time of your pages.
Against these disadvantages are its advantages. There are sites where you can download scripts for free and many sites where you can learn at least the rudiments of JavaScript programming without paying a cent.