Summary for the 68th meeting of Ecma TC39

Ecma Technical Committee 39 held three day meeting hosted by GoDaddy in Scottsdale, AZ on January 29th - January 31st, 2019. Agenda can be found here.

TC39 discussed 5 new proposals and 4 of them advanced to stage 1

• Freezing prototypes for stage 1
• Intl.DisplayNames for stage 1
• new.initialize for stage 1
• Iterator helpers for stage 1

Upon discussion at the committee, following proposal will not seek stage advancement.

• Private Symbols for stage 1

TC39 discussed 8 proposals for stage advancement and had updates presentation on 3 proposals

• Promise.allSettled
• Richer keys for stage 2

• Object.fromEntries for stage 4
• Well-formed JSON.stringify for stage 4
• String.prototype.{trimStart,trimEnd} for stage 4
• Array.prototype.{flat,flatMap} for stage 4

Following proposals did not reach consensus for stage advancement.

• Decorators for Stage 3
• Extended numeric literals status update, and consider restoring numeric separators to stage 3

Updates on proposals that are not seeking stage advancement

• Update on Set methods
• Private fields and methods remains with Stage 3 consensus, with renewed understanding of motivation
• Update on sequence properties in Unicode property escapes

TC39 discussed 4 Pull Requests to existing specification

• Normative: Treat IterationStatements uniformly in Annex B.3.5
• Add "name" property for classes as part of ClassDefinitionEvaluation
• %TypedArray%.prototype.sort stability

• Dynamic Modules Layering

Topics related to ECMAScript specification activities that were presented at the meeting.

• Amending the memory model to support ARMv8 LDA/STL codegen

• Security Implications of Error.prototype.stack

• Community feedback over globalThis, advocating for Global

  • globalThis follow up

• Private declarations

• Overloading method parameters between BigInt and Number

• Simplifying Set constructor

• Module Specifier for builtins

• Edge/Chakra Q&A from Microsoft

• Publishing the website

• The Community and Us

  • Communications: Discourse Strategy

• TC39 rationale - a proposed starting point

• ES2019 was finalized at this meeting
• We will begin the Royalty-Free opt-out period in February
• ES2019 adds following features to EcmaScript
  • Array#{flat,flatMap}
  • Object.fromEntries
  • String#{trimStart,trimEnd}
  • Symbol#description
  • try { } catch {} optional binding
  • EcmaScript as a syntactic superset of JSON
  • well-formed JSON.stringify
  • stable Array#sort
  • revised Function#toString

• TC39 welcomed 2019 Chair Group (Yulia Startsev, Aki Rose, Brian Terlson)
• TC39 to transition from RFTG to RFTC
• Report from the Ecma Secretariat
• ECMA-402 Status Update
• ECMA-404 Status Update
• Test262 Status Update
• Updates from the CoC Committee