> Look at collector.js, in the first dozen characters it's already using ECMAScript 6 standards like promises. According to caniuse, promises are supported by

> Look at collector.js, in the first dozen characters it's already using ECMAScript 6 standards like promises. According to caniuse, promises are supported by Chrome since v33, by Edge since v12, by Firefox since v29, and by Safari since 7.1. https://caniuse.com/promises https://caniuse.com/promises Both Chrome 33 and Firefox 29 were released in 2014.