Global attribute contenteditable
Informs that the element is available for editing by the user – you can delete text and enter a new one. Standard commands like undo, paste text from the buffer, etc. also work. Compatible with all browsers. Attribute contenteditable has a fixed set of values, it can be an empty string, true or false. Empty string or true indicate that the element is editable.
Global autofocus attribute
The autofocus attribute sets the default automatic input focus for HTML form fields when the page loads. The element that has the autofocus attribute set will have focus when the page loads (the cursor will blink in it if you start typing text from the keyboard – it will fall into the field with input focus). The attribute is an attribute without a value. It should be applied to the input, button or textarea tags and only one element per page, otherwise there will be a conflict.
Global class attribute
The global class attribute is a space-separated list of case-dependent classes of an element. Classes allow CSS and Javascript to select and access them using class selectors or functions such as the DOM document.getElementsByClassName methods. Developers use the class attribute all the time. Not only does it make styling easier, but it also helps keep your code organized and maintainable.