These days I look up individual features, and use the date-relative view, to assess how long it's been available. Normally I'll start porting features once they're solid across the main browser set, but with a polyfill or some alternative based on feature detection.
I held off on delivering ES6 native until 2017-2018, and used mainly Bable or sometimes hand written polys up to that point if I wanted to use features from cutting edge. There's some influence from your user-agent analytics as well to determine if there is a meaningful regression to leave people behind.
5 years is just the rough grasp, sometimes the new features are worth integrating sooner if they provide actual functional improvements for users. Generally, syntactic sugar is given less precedence especially when it would negatively impact usability of the product. Saving a few hours for development is far less valuable than saving even a few hundreds of users hours of frustration.
I held off on delivering ES6 native until 2017-2018, and used mainly Bable or sometimes hand written polys up to that point if I wanted to use features from cutting edge. There's some influence from your user-agent analytics as well to determine if there is a meaningful regression to leave people behind.
5 years is just the rough grasp, sometimes the new features are worth integrating sooner if they provide actual functional improvements for users. Generally, syntactic sugar is given less precedence especially when it would negatively impact usability of the product. Saving a few hours for development is far less valuable than saving even a few hundreds of users hours of frustration.