ES5: ECMAScript Standards for a Better Web Panelists: Allen Wirfs-Brock, Microsoft (Moderator) Brendan Eich, Mozilla Douglas Crockford, Yahoo! Mark S. Miller, Google

Final Document will be approved by TC39 next week. Ratification as official standard at December ECMA General Assembly meeting. ECMAScript 5 is Finished!

Final Document will be approved by TC39 next week.

Ratification as official standard at December ECMA General Assembly meeting.

What’s new in ES5 Enhanced Object Model & Reflection API Getter/Setter Properties Configurable Attributes Enumerable, Writable, Configurable Sealed/Frozen Objects Property Interrogation Object.create(proto,…) Technical Corrections Readonly NaN, undefined,etc. arguments is enumerable Array.prototype fully generic Etc. Etc… Strict Mode Enhanced Error Checking Tamed global object access Private eval scopes Native JSON Library Enhancements “ Array Extras” + reduce[Right] String trim Function bind Date ISO string format

Enhanced Object Model & Reflection API

Getter/Setter Properties

Configurable Attributes

Enumerable, Writable, Configurable

Sealed/Frozen Objects

Property Interrogation

Object.create(proto,…)

Technical Corrections

Readonly NaN, undefined,etc.

arguments is enumerable

Array.prototype fully generic

Etc. Etc…

Strict Mode

Enhanced Error Checking

Tamed global object access

Private eval scopes

Native JSON

Library Enhancements

“ Array Extras” + reduce[Right]

String trim

Function bind

Date ISO string format

What Does ECMA TC39 Actually Do? Codify successful browser/community innovation Mozilla “Array Extras” Polish promising innovations json2.js  ES5 JSON support Synthesize from browser experiments & user requirements __defineSetter__ + framework builder needs  ES5 Object Model enhancements and Reflection API Invent when necessary to solve real world problems Security & usability concerns  ES5 Strict Mode

Codify successful browser/community innovation

Mozilla “Array Extras”

Polish promising innovations

json2.js  ES5 JSON support

Synthesize from browser experiments & user requirements

__defineSetter__ + framework builder needs  ES5 Object Model enhancements and Reflection API

Invent when necessary to solve real world problems

Security & usability concerns  ES5 Strict Mode

What’s Next: ECMAScript “Harmony” Be a better language for writing: complex applications; libraries (possibly including the DOM) shared by those applications; code generators targeting the new edition. Switch to a testable specification, ideally a definitional interpreter hosted mostly in ES5. Improve interoperation, adopting de facto standards where possible. Keep versioning as simple and linear as possible. Support a statically verifiable, object-capability secure subset. Goals New features require concrete demonstrations. Keep the language pleasant for casual developers. Preserve the “start small and iteratively prototype” nature of the language. Requirements Minimize the additional semantic state needed beyond ES5. Provide syntactic conveniences for: good abstraction patterns; high integrity patterns; defined by desugaring into kernel semantics. Remove (via opt-in versioning or pragmas) confusing or troublesome constructs: Consider building on ES5 strict. Support virtualizability, for host object emulation Means 10 Year Release Cycle

Be a better language for writing:

complex applications;

libraries (possibly including the DOM) shared by those applications;

code generators targeting the new edition.

Switch to a testable specification, ideally a definitional interpreter hosted mostly in ES5.

Improve interoperation, adopting de facto standards where possible.

Keep versioning as simple and linear as possible.

Support a statically verifiable, object-capability secure subset.

New features require concrete demonstrations.

Keep the language pleasant for casual developers.

Preserve the “start small and iteratively prototype” nature of the language.

Minimize the additional semantic state needed beyond ES5.

Provide syntactic conveniences for:

good abstraction patterns;

high integrity patterns;

defined by desugaring into kernel semantics.

Remove (via opt-in versioning or pragmas) confusing or troublesome constructs: Consider building on ES5 strict.

Support virtualizability, for host object emulation

Panel Q&A? Panelists/ECMA TC39 Member Representatives: Allen Wirfs-Brock, Microsoft (Moderator) Brendan Eich, Mozilla Douglas Crockford, Yahoo! Mark S. Miller, Google

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