The italics() method of String values creates a string that embeds this string in an <i> element (<i>str</i>), which causes this string to be displayed as italic.

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 height attribute defines the vertical length of an element in the user coordinate system.

The dominant-baseline attribute specifies the dominant baseline, which is the baseline used to align the box's text and inline-level contents. It also indicates the default alignment baseline of any boxes participating in baseline alignment in the box's alignment context.

The k1 attribute defines one of the values to be used within the arithmetic operation of the <feComposite> filter primitive.

The right shift assignment (>>=) operator performs right shift on the two operands and assigns the result to the left operand.

The unary negation (-) operator precedes its operand and negates it.

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

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 spread (...) syntax allows an iterable, such as an array or string, to be expanded in places where zero or more arguments (for function calls) or elements (for array literals) are expected. In an object literal, the spread syntax enumerates the properties of an object and adds the key-value pairs to the object being created.