The <metadata> SVG element adds metadata to SVG content. Metadata is structured information about data. The contents of <metadata> should be elements from other XML namespaces such as RDF, FOAF, etc.

The <mpath> sub-element for the <animateMotion> element provides the ability to reference an external <path> element as the definition of a motion path.

The isFinite() function determines whether a value is finite, first converting the value to a number if necessary. A finite number is one that's not NaN or ±Infinity. Because coercion inside the isFinite() function can be surprising, you may prefer to use Number.isFinite().

The class keyword can be used to define a class inside an expression.

The Reflect namespace object contains static methods for invoking interceptable JavaScript object internal methods. The methods are the same as those of proxy handlers.

The <desc> element provides an accessible, long-text description of any SVG container element or graphics element.

The Set object lets you store unique values of any type, whether primitive values or object references.

Symbol is a built-in object whose constructor returns a symbol primitive — also called a Symbol value or just a Symbol — that's guaranteed to be unique. Symbols are often used to add unique property keys to an object that won't collide with keys any other code might add to the object, and which are hidden from any mechanisms other code will typically use to access the object. That enables a form of weak encapsulation, or a weak form of information hiding.

Number values represent floating-point numbers like 37 or -9.25.

The <clipPath> SVG element defines a clipping path, to be used by the clip-path property.