A character class matches any character in or not in a custom set of characters. When the v flag is enabled, it can also be used to match finite-length strings.

The keySplines attribute defines a set of Bézier curve control points associated with the keyTimes list, defining a cubic Bézier function that controls interval pacing.

The max attribute specifies the maximum value of the active animation duration.

A named backreference refers to the submatch of a previous named capturing group and matches the same text as that group. For unnamed capturing groups, you need to use the normal backreference syntax.

The opacity attribute specifies the transparency of an object or of a group of objects, that is, the degree to which the background behind the element is overlaid.

A UDP socket.

Below, you'll find a list of errors which are thrown by JavaScript. These errors can be a helpful debugging aid, but the reported problem isn't always immediately clear. The pages below will provide additional details about these errors. Each error is an object based upon the Error object, and has a name and a message.

The extends keyword is used in class declarations or class expressions to create a class that is a child of another class.

The filterUnits attribute defines the coordinate system for the attributes x, y, width and height.

The flood-color attribute indicates what color to use to flood the current filter primitive subregion.