Browsers that support ECMASCRIPT version 3:

Remember 3,4,5, skip to 8

Firefox 3+
Safari 4+
Chrome 5+
Internet Explorer 8+

There was no ECMASCRIPT version 4 (its a long story!)

Browsers that support ECMASCRIPT version 5:

These are one on from the ES3 browsers

Remember 4,5,6 skip to 9

Firefox 4+
Safari 5+ (except Date.prototype.toJSON etc)
Chrome 6+
Internet Explorer 9+ (except strict mode)

This is a simplified version of the Kangax compatibility table. I find this simplification easy to remember, but if you need full details visit Kangax.

ECMASCRIPT 2015 browsers

None of the browsers currently have full support for ES2015 but the latest versions of all major browsers support at least some of the specification.

ECMASCRIPT 2016 browsers

This specification has not been approved yet but Array.prototype. includes has been implemented in Firefox 44+

See Kangax ES Next for the latest details.