.. _Target the latest standardized JavaScript version:

Target the latest standardized JavaScript version
#################################################

Status
******

Accepted

Context
*******

The Open edX community must write JavaScript in a way that ensures future support and the availability of modern features.

Decision
********

The Open edX community must write JavaScript consistent with the latest
ECMA-262 specification in order to ensure future support, the largest
community, and the availability of modern features.

Consequence
***********

Not all browsers support the latest JavaScript features and syntax. To support this syntax in older browsers, the Open edX community must use `Babel`_.

Rejected Alternatives
*********************

.. _Reasons for rejecting CoffeeScript:

CoffeeScript
============

The Open edX codebase made heavy use of CoffeeScript for several years,
but its use at edX has now been officially deprecated. Most of the language
benefits of CoffeeScript were made available in JavaScript as of the ES2015 spec,
and CoffeeScript's community has largely moved on.

.. _Reasons for rejecting TypeScript:

TypeScript
==========

Several variants of typed JavaScript have grown in community popularity
recently, with `TypeScript`_ as the most popular. The Open edX community
believes adding typing to our JavaScript would raise the barrier to entry
for less experienced front end developers, and that using TypeScript in 
particular would lock us into a tool with an uncertain future (as we 
experienced with CoffeeScript). If typing is an absolute necessity for a
feature (e.g., an API client or sensitive business logic), `Flow`_ is 
recommended, as it can be incrementally added and evaluated alongside
non-typed code.

.. _Flow: https://flow.org/
.. _Typescript: https://www.typescriptlang.org/
.. _Babel: https://babeljs.io/