An AsyncIterator object is an object that conforms to the async iterator protocol by providing a next() method that returns a promise fulfilling to an iterator result object. The AsyncIterator.prototype object is a hidden global object that all built-in async iterators inherit from. It provides an [Symbol.asyncIterator]() method that returns the async iterator object itself, making the async iterator also async iterable.

JavaScript is designed on an object-based paradigm. An object is a collection of properties, and a property is an association between a name (or key) and a value. A property's value can be a function, in which case the property is known as a method.

The assignment (=) operator is used to assign a value to a variable or property. The assignment expression itself has a value, which is the assigned value. This allows multiple assignments to be chained in order to assign a single value to multiple variables.

As an XML dialect, SVG is namespaced. It is important to understand the concept of namespaces and how they are used if you plan to author SVG content. Namespaces are essential to user agents that support multiple XML dialects; browsers must be very strict. Taking the time to understand namespaces now will save you from future headaches.

The <polygon> SVG element defines a closed shape consisting of a set of connected straight line segments. The last point is connected to the first point.

The Array object, as with arrays in other programming languages, enables storing a collection of multiple items under a single variable name, and has members for performing common array operations.

The AggregateError object represents an error when several errors need to be wrapped in a single error. It is thrown when multiple errors need to be reported by an operation, for example by Promise.any(), when all promises passed to it reject.

The SharedArrayBuffer object is used to represent a generic raw binary data buffer, similar to the ArrayBuffer object, but in a way that they can be used to create views on shared memory. A SharedArrayBuffer is not a Transferable Object, unlike an ArrayBuffer which is transferable.

Trailing commas (sometimes called "final commas") can be useful when adding new elements, parameters, or properties to JavaScript code. If you want to add a new property, you can add a new line without modifying the previously last line if that line already uses a trailing comma. This makes version-control diffs cleaner and editing code might be less troublesome.

The method attribute indicates the method by which text should be rendered along the path of a <textPath> element.