Does CC2015+ support Json？

I have tested  cc2015 and cc2017 of AE,

the code:

var a = {"d":5};

var b = JSON.stringify(a);

var c = JSON.parse(b);

alert(c.d);

both them can alert 5!

Which JS specification supports ExtendScript engine?

everybody and book told me that is Third Edition (ECMA-262, old stuff).

but JSON.srtingify( ) and JSON.parse( ) is used  in ES5, right?

so, the CC2015+ could support ES5 ??? !