Async functions were a candidate for inclusion last year but were pushed out to this year. Shared memory, meanwhile, is coupled with atomics, providing atomic operations on shared memory locations.
ECMAScript 2017 also will include
Object.values/Object.entries. Similar to the
Object.entries would return arrays, with an ordering matching
Object.keys, with indices of all three resulting arrays matching the same key, value, or entry of an object, according to the ECMA proposal.
Object.getOwnPropertyDescriptors feature will simplify some common boilerplate, and allowing trailing commas in function parameter lists will provide for code attribution while making no changes to semantics. The proposal states that other languages, including Python and D, allow this capability so that code contributors can end a parameter addition with a trailing comma in a per-line parameters list, addressing the issue of code attribution.
Different features of ECMAScript are implemented in browsers at varying times. The most recent version of the specification, ECMAScript 2016, was approved last June and was limited in scope.