The RegExp.lastMatch static accessor property returns the last matched substring. RegExp["$&"] is an alias for this property.

The [@@iterator]() method of Iterator instances implements the iterable protocol and allows built-in iterators to be consumed by most syntaxes expecting iterables, such as the spread syntax and for...of loops. It returns the value of this, which is the iterator object itself.

The [@@iterator]() method of Segments instances implements the iterable protocol and allows Segments objects to be consumed by most syntaxes expecting iterables, such as the spread syntax and for...of loops. It returns a segments iterator object that yields data about each segment.

The every() method of Iterator instances is similar to Array.prototype.every(): it tests whether all elements produced by the iterator pass the test implemented by the provided function. It returns a boolean value.

The Math.E static data property represents Euler's number, the base of natural logarithms, e, which is approximately 2.718.

The Object.fromEntries() static method transforms a list of key-value pairs into an object.

The Object.seal() static method seals an object. Sealing an object prevents extensions and makes existing properties non-configurable. A sealed object has a fixed set of properties: new properties cannot be added, existing properties cannot be removed, their enumerability and configurability cannot be changed, and its prototype cannot be re-assigned. Values of existing properties can still be changed as long as they are writable. seal() returns the same object that was passed in.

The Intl.getCanonicalLocales() static method returns an array containing the canonical locale names. Duplicates will be omitted and elements will be validated as structurally valid language tags.

The trimStart() method of String values removes whitespace from the beginning of this string and returns a new string, without modifying the original string. trimLeft() is an alias of this method.

The padEnd() method of String values pads this string with a given string (repeated, if needed) so that the resulting string reaches a given length. The padding is applied from the end of this string.