1. Array.prototype.findIndex

    The `findIndex()` method returns the index of the first element in the array that satisfies the provided testing function.

  2. ECMAScript 2015 (ES6)

    Support for the ECMAScript 2015 specification. Features include Promises, Modules, Classes, Template Literals, Arrow Functions, Let and Const, Default Parameters, Generators, Destructuring Assignment, Rest & Spread, Map/Set & WeakMap/WeakSet and many more.

  3. javascript built-in: typedarray: findindex