ECMAScript 2016 (more commonly known as ES7). ES7 brings two new features: 1. Array.prototype.includes() 2. New exponential operator: **. Array.prototype.includes() We used .indexOf() to know if an element existed in an array. For example: ['my','dad','hates','me'].indexOf('dad') // 1 // I know it sounds confusing but the value 1 represents // the index at which the string 'dad' appears in the array. The key word is “exist.” .indexOf() is fine if we want to know at which index a given element appears. But if our goal is to know if a given element exists in an array, then .indexOf() is not the best option. And the reason is simple: When querying the existence of something we expect a boolean value, not a number. Array.prototype.includes() does exactly that. It determines if a given element exists in an array, returning true if it does, false otherwise. var life = ['mom', 'dad', 'brother'] ...