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

The Object.preventExtensions() static method prevents new properties from ever being added to an object (i.e. prevents future extensions to the object). It also prevents the object's prototype from being re-assigned.

The Math.atan() static method returns the inverse tangent (in radians) of a number, that is

The Number.parseInt() static method parses a string argument and returns an integer of the specified radix or base.

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

The Reflect.getPrototypeOf() static method is like Object.getPrototypeOf(). It returns the prototype of the specified object.

The Reflect.ownKeys() static method returns an array of the target object's own property keys.

The resizable accessor property of ArrayBuffer instances returns whether this array buffer can be resized or not.

The shift() method of Array instances removes the first element from an array and returns that removed element. This method changes the length of the array.

The Object.groupBy() static method groups the elements of a given iterable according to the string values returned by a provided callback function. The returned object has separate properties for each group, containing arrays with the elements in the group.