This chapter introduces the concepts, objects and functions used to work with and perform calculations using numbers and dates in JavaScript. This includes using numbers written in various bases including decimal, binary, and hexadecimal, as well as the use of the global Math object to perform a wide variety of mathematical operations on numbers.

An Iterator object is an object that conforms to the iterator protocol by providing a next() method that returns an iterator result object. All built-in iterators inherit from the Iterator class. The Iterator class provides a @@iterator method that returns the iterator object itself, making the iterator also iterable. It also provides some helper methods for working with iterators.

The SVG <stop> element defines a color and its position to use on a gradient. This element is always a child of a <linearGradient> or <radialGradient> element.

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

The <filter> SVG element defines a custom filter effect by grouping atomic filter primitives. It is never rendered itself, but must be used by the filter attribute on SVG elements, or the filter CSS property for SVG/HTML elements.

The <circle> SVG element is an SVG basic shape, used to draw circles based on a center point and a radius.

The <cursor> SVG element can be used to define a platform-independent custom cursor. A recommended approach for defining a platform-independent custom cursor is to create a PNG image and define a cursor element that references the PNG image and identifies the exact position within the image which is the pointer position (i.e., the hot spot).

JavaScript Date objects represent a single moment in time in a platform-independent format. Date objects encapsulate an integral number that represents milliseconds since the midnight at the beginning of January 1, 1970, UTC (the epoch).

The bitwise NOT (~) operator returns a number or BigInt whose binary representation has a 1 in each bit position for which the corresponding bit of the operand is 0, and a 0 otherwise.

The cap-height attribute defines the height of uppercase glyphs of the font within the font coordinate system.