They tried to cover this up. In designing ECMAScript 2015 (a.k.a. ES6, a.k.a. ES2015), the authors identified a number of undesirable side effects of their work. “Why worry?” they asked. “People will be so smitten with arrow functions and block-scope bindings that they won’t care about a few measly backwards-breaking changes.” Well I care, and I have evidence that suggests I’m not alone. Through a