The <line> SVG element is an SVG basic shape used to create a line connecting two points.

The nullish coalescing assignment (??=) operator, also known as the logical nullish assignment operator, only evaluates the right operand and assigns to the left if the left operand is nullish (null or undefined).

The class declaration creates a binding of a new class to a given name.

The JavaScript exception "octal escape sequences can't be used in untagged template literals or in strict mode code" occurs when octal escape sequences are used in strict mode string literals or untagged template literals.

The parseInt() function parses a string argument and returns an integer of the specified radix (the base in mathematical numeral systems).

The JavaScript exception "import declarations may only appear at top level of a module" occurs when an import declaration is not at the top level of a module. This might be because the import declaration is nested in other constructs (functions, blocks, etc.), or more often because the current file is not treated as a module.

The xlink:show attribute indicates how a linked resource should be opened and is meant for XLink-aware processors. In case of a conflict, the target attribute has priority, since it can express a wider range of values.

The y1 attribute is used to specify the first y-coordinate for drawing an SVG element that requires more than one coordinate. Elements that only need one coordinate use the y attribute instead.

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.

The y2 attribute is used to specify the second y-coordinate for drawing an SVG element that requires more than one coordinate. Elements that only need one coordinate use the y attribute instead.