Unobtrusive JavaScript, is a JavaScript that is separated from the web site's html markup. There are several benefits of using Unobtrusive JavaScript. Separation of concerns i.e the HTML markup is now clean without any traces of javascript. Page load time is better. It is also easy to update the code as all the Javascript logic is present in a separate file. We also get, better cache support, as all our JavaScript is now present in a separate file, it can be cached and accessed much faster.