One thing worth noting: MooTools, Prototype.js and some other libraries were fond of extending built-in object prototypes. jQuery wasn't. ES7 wanted to introdu

One thing worth noting: MooTools, Prototype.js and some other libraries were fond of extending built-in object prototypes. jQuery wasn't. ES7 wanted to introduce an Array#contains method. But due to prototype extension issues like https://esdiscuss.org/topic/having-a-non-enumerable-array-prototype-contains-may-not-be-web-compatible https://esdiscuss.org/topic/having-a-non-enumerable-array-pr... , they had to rename it to Array#includes ...