The Temporal API allows you to work with dates, times, time zones, and durations. It is more powerful than the Date API.
Web platform features
The link-parameters CSS property, param() modifier for the url() CSS function, and the #:~:param(…) URL fragment set custom CSS environment variables on an external resource, such as an SVG image, allowing the external resource to adapt its presentation based on the variables.
The Sanitizer API customizes the sanitization of HTML parsed and inserted into the DOM in a way that can prevent cross-site scripting attacks. You can use it with DOM APIs that accept a sanitizer option, such as parseHTML() or setHTML().
The <select> element's appearance, including the button, selected option, picker dropdown, and options, can be customized using CSS.
The corner-shape CSS property sets the shape of an element's corners when using border-radius, allowing for shapes other than rounded corners. For example, corner-shape: squircle is a shape in between a square and rounded corner.
The line-clamp CSS property limits the text in a block container to a certain number of lines. The prefixed -webkit-line-clamp is widely supported but only works with -webkit-box-orient: vertical in combination with display: -webkit-box or display: -webkit-inline-box.
Anchor positioning places an element based on the position of another element. For example, you can place a tooltip next to the content it references.
The loading="lazy" attribute for <video> and <audio> elements defers loading the media resource until the element is near the viewport. This matches the lazy-loading behavior for <img> and <iframe> elements.
The @function CSS at-rule defines a custom function that takes CSS values or custom properties as arguments, and returns a CSS value. It can be based on conditional logic such as by using the @media at-rule.
The if() CSS function is an inline conditional value that returns a value based on a set of conditions.
The calc-size() CSS function computes mathematical expressions that include height and width keyword values, for example calc-size(fit-content, size / 2). Not to be confused with the calc() CSS function, which cannot use keyword values.
#12
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.
#13
The JPEG XL image format is a raster graphics file format that supports animation, alpha transparency, and lossy as well as lossless compression.
#14
The attr() CSS function, in the context of any property, returns the value of an attribute of an HTML element, with the option to return it as a specific type or unit. You can set a default value for missing or invalid attributes.
The frame-sizing CSS property sets the size of an <iframe> element to that of it contents, to avoid scrolling in the iframe. Embedded documents allow this with the <meta name="responsive-embedded-sizing"> element and request resizing in the embedding page by calling window.requestResize().
Module import … with { type: "css" } statements load CSS modules as constructable stylesheets. Also known as CSS module scripts.
The flex-wrap: balance CSS declaration distributes items in a multi-line flex container such that each line has about the same number of items.
The moveBefore() DOM method relocates a node while preserving its state. For example, you can move the active element without losing focus, move an animated element without resetting the animation, or move an iframe without reloading its content.
The @view-transition CSS rule sets whether a document opts-in to transitions between documents in a multi-page application. Both the old and new document must opt-in for a transition to be triggered.
The <template for="…"> HTML element replaces the content at a named range or insertion point, marked by the processing instructions <?start name="…"> and <?end> or <?marker name="…">. You can use this to stream or "patch" partial updates into the document out of order.
The overlay CSS property, used as an allow-discrete CSS transition, prevents a top layer element, such as a popover or a <dialog>, from being removed from the top layer before it has finished animating. You can't set the value of the overlay property; only use it as transition property.
The border-shape CSS property sets the geometry of the border box, changing the shape of any applicable border, border image, focus outline, or shadow.
The stretch CSS keyword expands a box as needed to fit its contents until the maximum size is reached, without preserving the content's preferred aspect ratio.
The @custom-media CSS at-rule names a media query, which you can reuse in multiple @media rules.
