The WEBGL_compressed_texture_s3tc extension for WebGL 1.0 and 2.0 contexts adds S3TC compressed texture formats to compressedTexImage2D() and compressedTexSubImage2D().

The wheel event fires when the user moves a mouse wheel or similar spatially rotating input device.

The widows and orphans CSS properties set the minimum lines included in a text fragment created by page, column, or region breaks.

The XSLTProcessor API transforms XML documents into new XML or HTML documents, using XSLT stylesheets. You can use XSLT to convert data between different XML schemas or to convert XML data into web pages or PDF documents. Also known as Extensible Stylesheet Language Transformations.

The __proto__ property of objects partially exposes the prototype of an object.

The callee property of the arguments variable in a non-strict function body's local scope is the function that arguments belongs to.

The beforeunload event is fired when the current window is about to be unloaded. Typically this is used to display a dialog to confirm if users really want to leave the page when there is unsaved data that would be lost.

The window.devicePixelRatio property is the ratio of the size of one CSS pixel to the vertical size of one physical pixel on the current display device.

The escape() and unescape() built-in Javascript methods encode and unencode strings using percent encoding, where certain characters are replaced by hexadecimal escape sequences.

The getYear() and setYear() methods of Date objects get and set the year as an offset to 1900.

The toGMTString() method of Date objects is an alias to the toUTCString() method.

The window.external.AddSearchProvider() and window.external.IsSearchProviderInstalled() do nothing. Historically, they added external search providers to the browser.

The font-variant-position CSS property sets whether to use alternate glyphs for subscript and superscript text.

The audioTracks and videoTracks APIs for media elements switch audio and video tracks during playback.

The fastSeek() method seeks an <audio> or <video> element as fast as possible, by seeking to a keyframe instead of exactly the requested time.

The playback of multiple <video> or <audio> elements can be coordinated by a MediaController instance, for example to synchronize a sign-language interpreter track with the main video track.

The WEBGL_compressed_texture_pvrtc extension for WebGL 1.0 and 2.0 contexts adds PVRTC compressed texture formats to compressedTexImage2D() and compressedTexSubImage2D().

The text-overflow CSS property with a string value sets the string representing clipped text.

The rel="alternate stylesheet" attribute for the <link> HTML element offers an alternative style option to users.

The ime-mode CSS property sets the state of the input method editor for text fields.

The glyph-orientation-vertical CSS property sets the orientation of glyphs in text rendered in a vertical writing mode.

The :target-within CSS pseudo-class matches the element with an ID matching the URL fragment and its ancestors.

The <install> HTML element represents a button that, upon activation, prompts the user to choose whether to install a progressive web app.

The <usermedia> HTML element represents a button that, upon activation, toggles camera or microphone streams. If needed, it may prompt the user to choose whether to grant the page access to the camera and microphone.

The @mixin and @apply CSS at-rules define reusable style declaration fragments and apply them inside rules, optionally passing arguments.

The Ad Selection API facilitates advertisement sales by allowing sites to register users as part of an interest group or to choose which ads appear based on those interest groups, while minimizing the ability of advertisers to track specific members of the interest group.

The AmbientLightSensor API returns the current light level in lux of the ambient light level around the device.

A container performance entry measures time to render child elements, for container elements that have the containertiming attribute.

The @custom-media CSS at-rule names a media query, which you can reuse in multiple @media rules.

Device-bound session credentials is a protocol to request proof of possession of a private key. Regularly confirming key possession can help protect against cookie theft.