The JavaScript warning "test for equality (==) mistyped as assignment (=)?" occurs when there was an assignment (=) when you would normally expect a test for equality (==).

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

The @@unscopables data property of Array.prototype is shared by all Array instances. It contains property names that were not included in the ECMAScript standard prior to the ES2015 version and that are ignored for with statement-binding purposes.

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

The fill() method of Array instances changes all elements within a range of indices in an array to a static value. It returns the modified array.

The toLocaleString() method of Array instances returns a string representing the elements of the array. The elements are converted to strings using their toLocaleString methods and these strings are separated by a locale-specific string (such as a comma ",").

The forEach() method of Map instances executes a provided function once per each key/value pair in this map, in insertion order.

The Map[Symbol.species] static accessor property is an unused accessor property specifying how to copy Map objects.

The [Symbol.iterator]() method of Map instances implements the iterable protocol and allows Map objects to be consumed by most syntaxes expecting iterables, such as the spread syntax and for...of loops. It returns a map iterator object that yields the key-value pairs of the map in insertion order.

The clear() method of Map instances removes all elements from this map.