Alts on images, which allows you to optimize photos, it gives you the option of automatically filling out forms, which is useful when we want to check if the forms on the page are working properly. Web Developer plugin is able to clear cache and history and much more! Naturally, from the browser settings, you can also disable simpler, faster and more easily reversible solution is to install a multifunctional plug-in, which will be useful not only for studying Java Script. However, if you do not trust plugins, you can also disable JS from the browser level. In Chrome it is done like this: to verify correctness.
Java Script and as a result check