The ignoreCase accessor property of RegExp instances returns whether or not the i flag is used with this regular expression.

The unicodeSets accessor property of RegExp instances returns whether or not the v flag is used with this regular expression.

The Map.groupBy() static method groups the elements of a given iterable using the values returned by a provided callback function. The final returned Map uses the unique values from the test function as keys, which can be used to get the array of elements in each group.

The indexOf() method of TypedArray instances returns the first index at which a given element can be found in the typed array, or -1 if it is not present. This method has the same algorithm as Array.prototype.indexOf().

The Reflect.apply() static method calls a target function with arguments as specified.

The handler.isExtensible() method is a trap for the [[IsExtensible]] object internal method, which is used by operations such as Object.isExtensible().

The Reflect.isExtensible() static method is like Object.isExtensible(). It determines if an object is extensible (whether it can have new properties added to it).

The handler.apply() method is a trap for the [[Call]] object internal method, which is used by operations such as function calls.

The fileName data property of an Error instance contains the path to the file that raised this error.

The name data property of Error.prototype is shared by all Error instances. It represents the name for the type of error. For Error.prototype.name, the initial value is "Error". Subclasses like TypeError and SyntaxError provide their own name properties.