In April 2009, ECMA International retired the 4th Edition from development and re-assigned TC39 (development group) to the 5th Edition project. The 5th Edition spurred from disagreements inside the ECMASript 4 development group, which saw representatives from major companies like Microsoft, Yahoo and Mozilla trying to push a security and library update before the whole 4th edition would be complete.
All development on ECMAScript 5 is finished, tests being conducted in the summer of 2009. Companies like Microsoft, Opera or Mozilla have been actively involved in the testing process inside the TC39 group, trying to ensure future compatibilities between code and browser. ECMAScript 5 language specifications can be found here
. After the testing process, the language will be submitted to approval to the ECMA International General Assembly and will enter the standardization process at ISO/IEC until December 2009.
Developers will be able to request a “strict” mode compilation that will perform several tasks and security checks before executing the code. Some of these verifications perform static type checking, illegal constant assignment, check the validity of comparisons and reference name look-ups.Namespaces
The “const” declaration has been introduced just to store constants that previously relied on “var” declarations that could easily have been re-written by accident.Program Units
. A future release date for ECMAScript Harmony has not been unveiled by ECMA International.