The for...of statement executes a loop that operates on a sequence of values sourced from an iterable object. Iterable objects include instances of built-ins such as Array, String, TypedArray, Map, Set, NodeList (and other DOM collections), as well as the arguments object, generators produced by generator functions, and user-defined iterables.

The units-per-em attribute specifies the number of coordinate units on the "em square", an abstract square whose height is the intended distance between lines of type in the same type size. This is the size of the design grid on which glyphs are laid out.

The JavaScript exception "function statement requires a name" occurs when there is a function statement in the code that requires a name.

The rest parameter syntax allows a function to accept an indefinite number of arguments as an array, providing a way to represent variadic functions in JavaScript.

The text-decoration attribute defines whether text is decorated with an underline, overline and/or strike-through. It is a shorthand for the text-decoration-line and text-decoration-style properties.

The JavaScript exception "super() is only valid in derived class constructors" occurs when the super() call is used somewhere that's not the body of a constructor in a class with extends keyword.

The target attribute should be used when there are multiple possible targets for the ending resource, such as when the parent document is embedded within an HTML or XHTML document, or is viewed with a tabbed browser. This attribute specifies the name of the browsing context (e.g., a browser tab or an (X)HTML iframe or object element) into which a document is to be opened when the link is activated:

A marker trait representing types where a shared reference is considered unwind safe.

The JavaScript exception "negated character class with strings in regular expression" occurs when a v-mode character class is negated and may be able to match a string (more than one character).

A trait for giving a type a useful default value.