A WeakMap is a collection of key/value pairs whose keys must be objects or non-registered symbols, with values of any arbitrary JavaScript type, and which does not create strong references to its keys. That is, an object's presence as a key in a WeakMap does not prevent the object from being garbage collected. Once an object used as a key has been collected, its corresponding values in any WeakMap become candidates for garbage collection as well — as long as they aren't strongly referred to elsewhere. The only primitive type that can be used as a WeakMap key is symbol — more specifically, non-registered symbols — because non-registered symbols are guaranteed to be unique and cannot be re-created.

The for...in statement iterates over all enumerable string properties of an object (ignoring properties keyed by symbols), including inherited enumerable properties.

Scalable Vector Graphics (SVG) is an XML-based markup language for describing two-dimensional based vector graphics.

Configuring C# debugging

JavaScript applications consist of statements with an appropriate syntax. A single statement may span multiple lines. Multiple statements may occur on a single line if each statement is separated by a semicolon. This isn't a keyword, but a group of keywords.

Loops offer a quick and easy way to do something repeatedly. This chapter of the JavaScript Guide introduces the different iteration statements available to JavaScript.

Signing in to C# Dev Kit

The AsyncFunction object provides methods for async functions. In JavaScript, every async function is actually an AsyncFunction object.

When talking about text in SVG, we have to differentiate between two almost completely separate topics. One is the inclusion and display of text in an image, and the other is SVG fonts. The latter is described in a later section of the tutorial, while this page will focus on the first part: bringing text into an SVG image.

Modern browsers support using SVG within CSS styles to apply graphical effects to HTML content.