The includes() method of String values performs a case-sensitive search to determine whether a given string may be found within this string, returning true or false as appropriate.

The toSpliced() method of Array instances is the copying version of the splice() method. It returns a new array with some elements removed and/or replaced at a given index.

The JSON.parse() static method parses a JSON string, constructing the JavaScript value or object described by the string. An optional reviver function can be provided to perform a transformation on the resulting object before it is returned.

The Array[@@species] static accessor property returns the constructor used to construct return values from array methods.

The drop() method of Iterator instances returns a new iterator helper that skips the given number of elements at the start of this iterator.

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.

A WeakRef object lets you hold a weak reference to another object, without preventing that object from getting garbage-collected.

The Intl namespace object contains several constructors as well as functionality common to the internationalization constructors and other language sensitive functions. Collectively, they comprise the ECMAScript Internationalization API, which provides language sensitive string comparison, number formatting, date and time formatting, and more.

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