JavaScript: Iterator Prototype
New in JS2015.
Builtin iterators of JavaScript has a prototype object.
[see Iterator]
The Iterator Prototype object is denoted as β%IteratorPrototype%β by the JavaScript spec.
There's no direct syntax for it. But you can get it by
Reflect.getPrototypeOf ( Reflect.getPrototypeOf ( Object([][Symbol.iterator]) ))
// iterator's proprotype const itrp = Reflect.getPrototypeOf ( Reflect.getPrototypeOf ( Object([][Symbol.iterator]) )) ; // add a property itrp.x = 3; // inherited by all iterators console.log( [][Symbol.iterator].x ); // 3
You can add properties to this iterator prototype, so all builtin iterators will inherit it.