JavaScript (JS) is a lightweight interpreted (or just-in-time compiled) programming language with first-class functions. While it is most well-known as the scripting language for Web pages, many non-browser environments also use it, such as Node.js, Apache CouchDB and Adobe Acrobat. JavaScript is a prototype-based, garbage-collected, dynamic language, supporting multiple paradigms such as imperative, functional, and object-oriented.

The Float64Array typed array represents an array of 64-bit floating point numbers in the platform byte order. If control over byte order is needed, use DataView instead. The contents are initialized to 0 unless initialization data is explicitly provided. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).

The Atomics namespace object contains static methods for carrying out atomic operations. They are used with SharedArrayBuffer and ArrayBuffer objects.

A WeakSet is a collection of garbage-collectable values, including objects and non-registered symbols. A value in the WeakSet may only occur once. It is unique in the WeakSet's collection.

The color attribute is used to provide a potential indirect value, currentColor, for the fill, stroke, stop-color, flood-color, and lighting-color attributes.

The unary plus (+) operator precedes its operand and evaluates to its operand but attempts to convert it into a number, if it isn't already.

The amplitude attribute controls the amplitude of the gamma function of a component transfer element when its type attribute is gamma.

The exponentiation (**) operator returns the result of raising the first operand to the power of the second operand. It is equivalent to Math.pow(), except it also accepts BigInts as operands.

The clip-path presentation attribute defines or associates a clipping path with the element it is related to.

The decoding attribute, valid on <image> elements, provides a hint to the browser as to whether it should perform image decoding along with rendering other content in a single presentation step that looks more "correct" (sync), or render and present the other content first and then decode the image and present it later (async). In practice, async means that the next paint does not wait for the image to decode.