The Promise.race() static method takes an iterable of promises as input and returns a single Promise. This returned promise settles with the eventual state of the first promise that settles.

The indexOf() method of String values searches this string and returns the index of the first occurrence of the specified substring. It takes an optional starting position and returns the first occurrence of the specified substring at an index greater than or equal to the specified number.

The arguments.callee data property contains the currently executing function that the arguments belong to.

The [@@iterator]() method of arguments objects implements the iterable protocol and allows arguments objects to be consumed by most syntaxes expecting iterables, such as the spread syntax and for...of loops. It returns an array iterator object that yields the value of each index in the arguments object.

The Intl.PluralRules object enables plural-sensitive formatting and plural-related language rules.

The [@@match]() method of RegExp instances specifies how String.prototype.match() should behave. In addition, its presence (or absence) can influence whether an object is regarded as a regular expression.

The [@@replace]() method of RegExp instances specifies how String.prototype.replace() and String.prototype.replaceAll() should behave when the regular expression is passed in as the pattern.

The Symbol.unscopables static data property represents the well-known symbol @@unscopables. The with statement looks up this symbol on the scope object for a property containing a collection of properties that should not become bindings within the with environment.

The flatMap() method of Array instances returns a new array formed by applying a given callback function to each element of the array, and then flattening the result by one level. It is identical to a map() followed by a flat() of depth 1 (arr.map(...args).flat()), but slightly more efficient than calling those two methods separately.

The includes() method of Array instances determines whether an array includes a certain value among its entries, returning true or false as appropriate.