These rules determine in which format and with which command set your application can access the service, as well as what data this service can return in a response. The HTML tag that should encompass all the JS code you write. Using Css style we can hide or show HTML elements in javascript.Css provides properties such as block and none to hide/show the HTML elements.. You run JavaScript from inside your HTML webpages. Using a variable inside XSL:text in roundrect tag in XSLT . Below is the example −. A JavaScript file will have extension as .js and it will be included in HTML files using