The maskUnits attribute indicates which coordinate system to use for the geometry properties of the <mask> element.

Classes are a template for creating objects. They encapsulate data with code to work on that data. Classes in JS are built on prototypes but also have some syntax and semantics that are unique to classes.

The pointsAtY attribute represents the y location in the coordinate system established by attribute primitiveUnits on the <filter> element of the point at which the light source is pointing.

The marker-end attribute defines the arrowhead or polymarker that will be drawn at the final vertex of the given shape.

A unicode character class escape is a kind of character class escape that matches a set of characters specified by a Unicode property. It's only supported in Unicode-aware mode. When the v flag is enabled, it can also be used to match finite-length strings.

The panose-1 attribute indicates the Panose-1 number of a font face.

The lang attribute specifies the primary language used in contents and attributes containing text content of particular elements.

The void operator evaluates the given expression and then returns undefined.

The if...else statement executes a statement if a specified condition is truthy. If the condition is falsy, another statement in the optional else clause will be executed.

The try...catch statement is comprised of a try block and either a catch block, a finally block, or both. The code in the try block is executed first, and if it throws an exception, the code in the catch block will be executed. The code in the finally block will always be executed before control flow exits the entire construct.