I run Firefox with an extension called NoScript, it blocks javascript from all domains until you allow each domain you want. It is one of the most popular addons for Firefox, and has been for some time now. This is handy as it speeds up browsing as I don't have to wait for adverts to load up as they are mostly served up using Javascript, like Google Ads. It also prevents most of these dodgy ad networks sticking tracker cookies on your browser, or using malicious coding in adverts, which has fucked over many a social networking website user in the past.
You also need to remember all of the search engine bots ignore javascript as it saves on bandwidth, speeds up a per page crawl, and stops the potential of them being infected/exploited by malicious code. If your site cannot be browsed with javascript disabled, it will not be crawled, which is bad for SEO.
Also some special browsers like screen readers may have javascript disabled, though I am not sure as I haven't tested any. Either way having a site that does not work with javascript disabled is bad for accessibility.