.github/CHANGELOG-v4.md
# Babel v4 Changelog
## 4.7.16
* **Bug Fix**
* Fix constructor spreading of typed arrays.
* Fix break/continue/return aliasing of non-loops in block scoping transformer.
## 4.7.15
* **Bug Fix**
* Fix constructor spreading of collections.
## 4.7.14
* **Bug Fix**
* Fix constructor spreading of `Promise`.
* **Internal**
* Deprecate remaining playground transformers and abstract references.
## 4.7.13
* **Bug Fix**
* Handle comments on use strict directives.
* Fix assignment patterns with a left side pattern.
* **Polish**
* Special case `this` when doing expression memoisation.
## 4.7.12
* **Bug Fix**
* Deprecate `playground.methodBinding`.
## 4.7.11
* **Bug Fix**
* Fix unicode regexes stripping their unicode flag before being passed on two `regexpu`.
## 4.7.10
* **Internal**
* Deprecate `playground.methodBinding` and `playground.objectGetterMemoization`.
* **Bug Fix**
* Fix `inputSourceMap` option. Thanks [@Rich-Harris](https://github.com/Rich-Harris)!
## 4.7.9
* **Polish**
* Allow `inputSourceMap` to be set to `false` to skip the source map inference.
* Infer computed literal property names.
* **Bug Fix**
* Fix nested labeled for-ofs.
* Fix block scoping `break` colliding with the parent switch case.
* **Internal**
* Upgrade `acorn-babel`.
## 4.7.8
* **Bug Fix**
* Fix computed classes not properly setting symbols.
## 4.7.7
* **Bug Fix**
* Fix `types` API exposure.
## 4.7.6
* **Bug Fix**
* Fix non-Identifier/Literal computed class methods.
* **Polish**
* Add a fallback if `stack` on an error is unconfigurable.
* Hoist `esModule` module declarations to the top of the file to handle circular dependencies better.
## 4.7.5
* **Bug Fix**
* Don't remap` break`s to call the iterator return.
* **Polish**
* Use a different helper for computed classes for much nicer output. Also fixes a bug in symbols being non-enumerable so they wouldn't be set on the class.
## 4.7.4
* **Bug Fix**
* Rewrite named function expressions in optional async function transformers.
* Hoist directives.
* Remove `Number` from the list of valid `runtime` constructors.
* **Internal**
* `spec.typeofSymbol` transformer has been renamed to `es6.symbols`.
## 4.7.2
* **New Feature**
* `"both"` option for `sourceMap`.
* Add output types to external helpers. Thanks [@neVERberleRfellerER](https://github.com/neVERberleRfellerER)!
* **Bug Fix**
* Fix node duplication sometimes resulting in a recursion error.
* Ignore `break`s within cases inside `for...of`.
* **Polish**
* Split up variable declarations and export declarations to allow easier transformation.
## 4.7.0
* **Bug Fix**
* Add `alternate` to list of `STATEMENT_OR_BLOCK` keys.
* Add support for module specifiers to `t.isReferenced`.
* **New Feature**
* Add `inputSourceMap` option.
* **Polish**
* Throw an error on different `babel` and `babel-runtime` versions.
* Replicate module environment for `babel-node` eval.
* Clean up classes output.
* **Spec Compliance**
* Make it illegal to use a rest parameter on a setter.
## 4.6.6
* **Bug Fix**
* Fix incorrect method call in `utility.deadCodeElimination` transformer.
* Fix `es6.blockScopingTDZ` transformer duplicating binding nodes.
## 4.6.5
* **Internal**
* `useStrict` transformer has been renamed to `strict`.
## 4.6.4
* **Bug Fix**
* Fix `ForOfStatement` not properly inheriting labels.
* When in closure mode in block scoping transformer, properly check for variable shadowing.
* **New Feature**
* New `utility.inlineEnvironmentVariables` and `utility.inlineExpression` transformers.
## 4.6.3
* **Bug Fix**
* Fix `arguments` being incorrectly aliased in arrow function rest parameter optimisation.
* Make deoptimisation trigger safer.
* **New Feature**
* Flow types are now retained when blacklisting the `flow` transformer.
## 4.6.1
* **Bug Fix**
* Fix generators in template directory being transformed.
* Fix exposure of `util` for plugins.
## 4.6.0
* **New Feature**
* Desugar sticky regexes to a new constructor expression so it can be handled by a polyfill.
* **Spec Compliance**
* `for...of` now outputs in a lengthy `try...catch` this is to ensure spec compliance in regards to iterator returns and abrupt completions. See [google/traceur-compiler#1773](https://github.com/google/traceur-compiler/issues/1773) and [babel/babel/#838](https://github.com/babel/babel/issues/838) for more information.
* **Polish**
* Rest parameters that are only referred to via number properties on member expressions are desugared into a direct `arguments` reference. Thanks [@neVERberleRfellerER](https://github.com/neVERberleRfellerER)!
* `$ babel` no longer exits on syntax errors.
* **Internal**
* Upgrade `browserify`.
* Upgrade `source-map`.
* Publicly expose more internals.
## 4.5.5
* **Polish**
* Delete old extensions when overriding them in `babel/register`.
## 4.5.3
* **Bug Fix**
* Fix whitelisting logic for helper build script.
## 4.5.2
* **New Feature**
* `returnUsedHelpers` option and add whitelist to `buildHelpers`.
* **Bug Fix**
* Fix function arity on self referencing inferred named functions.
* **Internal**
* Bump `acorn-babel`.
* Start converting source to ES6...
## 4.5.1
**Babel now compiles itself!**
## 4.5.0
* **New Feature**
* Add `.babelrc` support.
* **Bug Fix**
* Move use strict directives to the module formatter bodies.
* **Internal**
* Make default `bin/babel` behaviour to ignore non-compilable files and add a `--copy-files` flag to revert to the old behaviour.
## 4.4.6
* **Bug Fix**
* Fix extending a class expression with no methods/only constructor. Thanks [@neVERberleRfellerER](https://github.com/neVERberleRfellerER)!
* Allow `MemberExpression` as a valid `left` of `ForOfStatement`.
* **Polish**
* Throw an error when people try and transpile code with the `@jsx React.DOM` pragma as it conflicts with the custom jsx constructo method detection.
* Crawl all comments for `@jsx` pragma.
* **Internal**
* Upgrade `chalk`.
* Upgrade `core-js`.
## 4.4.5
* **Internal**
* Remove function self reference optimisation.
## 4.4.4
* **Bug Fix**
* Handle inferred function ids to be reassigned and deopt to a slower but working equivalent.
* Don't unpack array patterns that have more elements than their right hand array expression.
* **Polish**
* Improve syntax highlighting in the code frame. Thanks [@lydell](https://github.com/lydell)!
* **Internal**
* Upgrade `acorn-babel`.
## 4.4.3
* **Bug Fix**
* Fix `for...of` iterator break returns being duplicated.
* Only call `return` on the iterator if it exists.
* **Internal**
* Rename `selfContained` transformer to `runtime`.
## 4.4.2
* **New Feature**
* Add `moduleId` option for specifying a custom module id.
## 4.4.0
* **New Feature**
* `/*** @jsx NAMESPACE **/` comments are now honored by the `react` transformer.
* `getModuleName` option.
* Infer function expression names. Thanks [@RReverser](https://github.com/RReverser)!
* **Bug Fix**
* Add proper control flow for tail recursion optimisation.
* **Internal**
* Remove useless `format` options and move the `format.compact` option to `format`.
* **Polish**
* Newline handling of the code generator has been heavily improved.
* Code generator now deopts whitespace if the input size is >100KB.
## 4.3.0
* **Breaking Change**
* Remove `commonStandard` module formatter and make it the default behaviour of all the strict module formatters.
## 4.2.1
* **Polish**
* Add auxiliary comment to let scoping closure flow control.
## 4.2.0
* **Polish**
* Use an assignment instead of a define for `__esModule` in loose mode.
* **Internal**
* Add error for `eval();` usage and enable strict mode for parsing.
## 4.1.0
* **New Feature**
* Add `BABEL_CACHE_PATH` and `BABEL_DISABLE_CACHE` environment variables.
* **Internal**
* Replace many internal util functions with modules. Thanks [@sindresorhus](https://github.com/sindresorhus)!
## 4.0.2
* **Bug Fix**
* Fix generators not properly propagating their internal declarations.
* **Polish**
* Update setter param length error message.
* Use ranges on dependencies.
## 4.0.0
* 6to5 is now known as Babel.
* Global helpers/runtime has now been given the more descriptive name of "external helpers".