Recently while building a Cordova based app, few users complained that they were seeing blank pages or cryptic error messages. Someone mentioned they were on iOS9. Over the weekend, as I ran the app on a simulator, I noticed an error in Safari. And, that’s when I realized ES6 features and syntax is not fully supported in iOS9.  Please see here: ES6 Compatibility (check unstable platforms)

So be-aware of ES6 features compatibility (unless you can transpile/polyfill every bit of code)