The ping attribute can be included in link tags to notify the server when the link is clicked. This can be used for tracking purposes.

The 〈output〉 tag is the standard HTML element in which the result of any user action or calculation performed can be shown. The result can inserted inside the tag using Javascript.

HTML videos can be lazily loaded using the preload attribute of the 〈video〉element. preload="none" needs to be set to disable pre-loading of the video.

Variable fonts is a new font technology that allows a single font file to store multiple variations of the font. Variable fonts are going to bring a major change in web design.

The Array.fill() method can be used to fill an array with a specific value, starting from a given index and ending upto another index.

Flattening an array refers to the process taking an input array, which may itself contain n-dimensional arrays as its elements, to a single array. This can be done in Javascript using the flat() method.

The Intl.NumberFormat object can be used to format a number as a currency using Javascript. Various options can be set to customize format of currency code, comma / decimal separators etc.

The finally() callback can be used to know whether the Promise was settled. We don't care whether it was resolved or rejected.

The nullish coalescing operator has been newly introduced in Javascript. This can be used to give default values if a variable is either null or undefined.

Time delay for setTimeout() / setInterval() methods executing on inactive browser tabs are set to one second regardless of their value defined in code.

When a fixed-position modal dialog is opened, scrollbars on the page can be removed by dynamically setting overflow:hidden CSS for the 〈body〉tag.

Pull-to-refresh feature on mobile browsers that refreshes the page, can be disabled using the overscroll-behaviour CSS property.

The "decoding" attribute can be included for an 〈img〉tag to specify whether to decode the image in parallel or along with the rest of the page content.

The Object.seal() method seals an object. After an object gets sealed, no new properties can be added to it.

The Object.freeze() method can make an object or array immutable. No changes can be made to that object once it gets immutable.

Many next generation CSS properties and APIs have been introduced in browsers lately. These can help in creation of user interfaces that were previously not possible or were difficult to achieve.

Hashbang comments is the third type of syntax for adding comments to Javascript code. This comment can specify the Javascript interpreter that is to be used to execute the code within a script file or a module.

A stylesheet can include the disabled attribute in its markup to prevent it from being downloaded on page load. Later when the stylesheet needs to loaded on demand, its disabled attribute can be removed with Javascript.

Numeric separators can be used to improve readability of large numbers. For example the number 111111111111111111111111, which is difficult to read, can be alternately written as 111_111_111_111_111_111_111_111

To prevent situations where we would not like the browser to autofill the password field in a form, the autocomplete=new-password attribute can be used.