HTML details element
Simply show or hide content without any scripts.
form one liner resets
Check out how to reset form using JavaScript, jQuery or even raw HTML.
Blog
advanced frontend topics with short solutions and explanations
HTMLdeveloped by Web Hypertext Application Technology Working Group (WHATWG)
The HyperText Markup Language or HTML is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScript.
References - wiki