The await using declaration declares block-scoped local variables that are asynchronously disposed. Like const, variables declared with await using must be initialized and cannot be reassigned. The variable's value must be either null, undefined, or an object with a [Symbol.asyncDispose]() or [Symbol.dispose]() method. When the variable goes out of scope, the [Symbol.asyncDispose]() or [Symbol.dispose]() method of the object is called and awaited, to ensure that resources are freed.

A block statement is used to group zero or more statements. The block is delimited by a pair of braces ("curly braces") and contains a list of zero or more statements and declarations.

Private elements are counterparts of the regular class elements which are public, including class fields, class methods, etc. Private elements get created by using a hash # prefix and cannot be legally referenced outside of the class. The privacy encapsulation of these class elements is enforced by JavaScript itself. The only way to access a private element is via dot notation, and you can only do so within the class that defines the private element.

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 RegExp object is used for matching text with a pattern.

Apart from graphic primitives like rectangles and circles, SVG offers a set of elements to embed other types of content in images as well.

The JavaScript exception "form must be one of 'NFC', 'NFD', 'NFKC', or 'NFKD'" occurs when an unrecognized string is passed to the String.prototype.normalize() method.

The do...while statement creates a loop that executes a specified statement as long as the test condition evaluates to true. The condition is evaluated after executing the statement, resulting in the specified statement executing at least once.

The <feSpecularLighting> SVG filter primitive lights a source graphic using the alpha channel as a bump map. The resulting image is an RGBA image based on the light color. The lighting calculation follows the standard specular component of the Phong lighting model. The resulting image depends on the light color, light position and surface geometry of the input bump map. The result of the lighting calculation is added. The filter primitive assumes that the viewer is at infinity in the z direction.

The <feImage> SVG filter primitive fetches image data from an external source and provides the pixel data as output (meaning if the external source is an SVG image, it is rasterized.)