The JavaScript exception "super() called twice in derived class constructor" occurs when the super() is called a second time for a given derived class constructor.

Public fields are writable, enumerable, and configurable properties defined on each class instance or class constructor.

The multiplication assignment operator `*=`.

The reduce() method of Array instances executes a user-supplied "reducer" callback function on each element of the array, in order, passing in the return value from the calculation on the preceding element. The final result of running the reducer across all elements of the array is a single value.

The unary logical negation operator `!`.

The substring() method of String values returns the part of this string from the start index up to and excluding the end index, or to the end of the string if no end index is supplied.

The remainder operator `%`.

The return() method of Generator instances acts as if a return statement is inserted in the generator's body at the current suspended position, which finishes the generator and allows the generator to perform any cleanup tasks when combined with a try...finally block.

A mutable iterator over the values of a `HashMap`.

The Symbol.match static data property represents the well-known symbol Symbol.match. The String.prototype.match() method looks up this symbol on its first argument for the method used to match an input string against the current object. This symbol is also used to determine if an object should be treated as a regex.