CHANGELOG.md

Changelog

Tags:

• [New Feature]
• [Bug Fix]
• [Spec Compliancy]
• [Breaking Change]
• [Documentation]
• [Internal]
• [Polish]

Note: Gaps between patch versions are faulty, broken or test releases.

See CHANGELOG - 6to5 for the pre-4.0.0 version changelog.

6.0.16

• Internal
• Instead of throwing on a foreign node path. Ignore it and create a new one.
• Bug Fix
• Ensure there's a newline after prepended original shebang.
• Ignore non-origin template nodes when replacing placeholders in babel-template.
• Fix runtime plugin helper generation.
• Fix bug where async class methods weren't having their awaits converted to yields in the async to generator helper.

6.0.15

• Bug Fix
• Fix async function remap helper from outputing incorrect calls causing wrong scoping.

6.0.14

• Spec Compliancy
• Update exponentiation operator precedence.
• Fix parser bug where arrow functions have a higher precedence than they should.
• Bug Fix
• Fix SystemJS module formatter exporting function parameters.
• Ensure that invalid identifier JSX attribute keys are quoted when transforming to calls.
• Fix ES3 property literal plugin.
• Fix parameters after defaults in arrow functions refering to the wrong arguments.

6.0.13

• Bug Fix
• Don't consider uncomputed object method property identifier to be a reference.

6.0.12

• Bug Fix
• Rename misspelt babel-plugin-transform-class-constructor-call package.
• Add strict mode plugin to module transforms.
• Only ignore cloning of plugin instances when cloning babelrc configs.
• Add shebang to bin file in babel complain package.
• Remove asserts from babel-transform-regenerator as we may have multiple packages interacting.
• Add babel-plugin-transform-es2015-modules-commonjs to babel-preset-es2015.

6.0.0

• Internal
• Split up internals into packages.
• Breaking Change
• Remove loose option in favor of plugin options.
• Remove optional, whitelist and blacklist options since plugins are now explicitly defined.
• Plugins now just return a plain object rather than construct a Plugin instance.
• Change the signature of visitor methods to .call(state, path, state) rather than .call(path, node, parent, scope, state).
• All plugin traversals are now merged for performance.
• The MethodDefinition node type has been renamed to ClassMethod and it's FunctionExpression value property has been coerced into the main method node.
• The Property node type has been renamed to ObjectProperty.
• The Property node type with the boolean flag method has been renamed to ObjectMethod and it's FunctionExpression value property has been coerced into the main method node.
• The Literal node type has been unoverloaded and split into BooleanLiteral, RegexLiteral, NumberLiteral, StringLiteral and NullLiteral.
• The SpreadProperty (from object-rest-spread) node type has been split into RestProperty (for ObjectPattern) and SpreadProperty (for ObjectExpression)
• Remove module.exports export interop for CommonJS module formatter.
• externalHelpers option has been moved into the plugin babel-plugin-external-helper-2.
• New Feature
• Add plugin options.
• Add callable class constructor.

5.8.26

• Internal
• Republish to get fix for runtime typeof-react-element helper.

5.8.25

• Internal
• Rename define method to avoid webpack assuming those files are AMD.

5.8.24

• Spec Compliancy
• Updated optimisation.react.inlineElements transformer to React 0.14 output. Thanks @spicyj!
• Polish
• Add support for evaluating more static nodes. Thanks @hzoo!

5.8.23

• Bug Fix
• Fix a bug where pushed scope bindings weren't properly being registered.

5.8.22

• Bug Fix
• Fix bug causing regexes to cause a syntax error after a block.
• Internal
• Expose File.

5.8.21

• New Feature
• Add support for Flow export types.
• Bug Fix
• Fix flow type annotations on object properties being lost.
• Fix bug effecting nested arrow functions.
• Check valid export default function/class token when parsing export default before converting to a declaration to avoid turning expressions into declarations.
• Polish
• Add an exception to non-existent bindings when checking if we need to wrap block scoping blocks in a closure.
• Make comment retainment for multiple replacement nodes more predictable.
• Internal
• Remove operator property from AssignmentPattern nodes.
• Update es7.asyncFunctions and es7.objectRestSpread to stage 2.

5.8.13-5.8.20

The CHANGELOG was broken for these releases. Git tags were not pushed in the correct order and are therefore incorrect. It's recommended you NOT use any versions within this range.

• New Feature
• Add es6.spec.modules transformer.
• Bug Fix
• Don't register export declarations as a module binding.
• Register import bindings to the specifier instead of the declaration.
• export * should not export default.
• Clear `rawValue from JSX attribute values to avoid outputting the raw source verbatim.
• Add support for boolean flow literals.
• Fix bug where files that babel can compile weren't being written when ignored with the --copy-files flag.
• Create new raw identifiers instead of cloning the original user one when exploding export specifiers to fix source map issues resulting in incorrect locations.
• Break on hitting a terminator paren triggering character to avoid pushing multiple starting parens.
• Consider comment starting character to be a terminatorless separator to avoid starting comments breaking terminatorless nodes.
• Internal
• Use json5 for parsing .babelrc files and JSON for package.json.
• Update Regenerator dependency to 0.8.35.
• Remove flow types from being scope tracked.
• Polish
• Only register export declarations in scope tracking if they're of a valid type.
• Only output code frame and message on syntax errors in CLI.
• Set decorated initialisers that have no initialiser to undefined.
• Optimise common typeof cases in es6.spec.symbols transformer.

5.8.12

• Bug Fix
• Fix bug in lookahead causing decorators to be cleared.

5.8.11

• Bug Fix
• Check if module options are nully instead of falsy to allow empty strings as moduleRoot etc.
• Fix bug where reassigning the rest parameter wouldn't result in a deoptimisation.

5.8.9

• Bug Fix
• Fix issue in parser where the flow plugin wasn't using state to refer to whether it as in a type or not causing lookaheads to cause breakages.

5.8.8

• Bug Fix
• Fix comments not being attached if they're touching the start of their node.

5.8.7

• Never published, environment issues, again.

5.8.6

• Bug Fix
• Remove rawValue for JSX inner text.

5.8.5

• Polish
• Rewrite parentheses insertion for terminatorless nodes such as BreakStatement to be much more stable and cleaner.
• Use Object.setPrototypeOf and fallback to __proto__ in inherits helper.

5.8.2-5.8.4

Issues with publish process.

5.8.1

• Bug Fix
• Fix regression where async arrow functions couldn't have type annotation parameters.
• Output type annotations of type instantiation parameters.
• Polish
• Prepend to highest loop when performing rest parameter allocation optimisation.
• Add comment attachment to parser.
• Add support for retaining inner comments of empty blocks.

5.8.0

• Never released due to publish environment issues.

5.7.4

• Bug Fix
• Fix comments containg @flow being completely removed from output rather than just the specific directive.

5.7.3

• Bug Fix
• Add shim file for broken file path that old versions of the CLI would attempt to use.

5.7.2

• Bug Fix
• Fix performance issue in code generator when comment columns would attempt to match up in compact mode causing large amounts of whitespace.
• Fix single line comments not outputting a newline in compact mode.
• Polish
• Add support for flow return types for arrow functions.

5.7.1

• Bug Fix
• Add back mistakenly removed replaceWithSourceString method.

5.7.0

• Bug Fix
• Deopt on spread elements when performing array destructuring unpack optimisation.
• New Feature
• Add shouldPrintComment option to control comment output.
• Add .babelignore file to be consistent with other tools.
• Allow .babelrc configs to be specified via package.json.
• Polish
• Don't ignore comments when using compact: true option.
• Add support for Flow import typeof.
• Fix incorrect inheritance method position when using loose mode classes and constructor isn't the first item.
• Internal
• Completely fork Acorn with babylon.
• Rewrite build system to accommodate for multiple packages.

5.6.17

• Bug Fix
• Fix CodeGenerator.findCommonStringDelimiter causing a stack overflow.

5.6.16

• Internal
• Fix recast version to avoid pulling in a newer version.
• New Feature
• Add support for functions in util.shouldIgnore.
• Polish
• Strip flow directives in flow transformer.
• Add a check for out of bounds default parameters, drastically improving performance and removes engine deoptimisations.
• Various performance optimisations by @samccone 💅✨
• Delay this assignment when referencing this inside an arrow function pre-bare super in derived class constructors.
• Split up class body pushing if the constructor is in the wrong order.
• Bug Fix
• Fix hoisting of ForInStatement init variables in system module formatter.
• PathHoister: Don't hoist to the same function as their original paths function parent.
• PathHoister: Push each violation paths ancestry to the breakOnScopePaths collection to avoid constant hoisting to nested paths.fix tail call recursion on functions with less arguments than parameters.
• Disallow super.* before super() in derived class constructors.
• Properly regenerate scope for replaced nodes. Thanks @loganfsmyth!
• Move up template literal simplification logic to avoid breaking on single elements.

5.6.13-5.6.15

• Setting up automatic Travis releases.

5.6.12

• Bug Fix
• Fix finding parent for top-level shadowed functions.

5.6.11

** Internal

• Merge es6.parameters.rest and es6.parameters.default transformers. See commit c0fd4c1f9e0b18231f585c4fa793e4cb0e01aed1 for more info.

5.6.10

• Bug Fix
• Fix faulty internal require check.
• Polish
• Add support for trailing commas in arrow function parameter lists.

5.6.8

• Bug Fix
• Fix binary expressions colliding with unary expression operators in compact mode.
• Fix node properties being set to null when using computed properties.

5.6.7

• Bug Fix
• Fix hoisting of ForXStatement left vars when inserting a block scoping IIFE.
• Polish
• Combine all leading computed property initialisers into the root object in loose mode.
• Internal
• Deprecate returning of replacement strings from visitor methods.

5.6.6

• Bug Fix
• Fix weird parser bug where void type annotations were being parsed as keywords causing the tokeniser to lose track of context.

5.6.5

• Bug Fix
• Fix nested functions causing rest parameter optimisation to not properly detect when it should deopt on a reference.
• Internal
• Update Regenerator 0.8.31.

5.6.4

• Internal
• Add ParenthesizedExpression node type.

5.6.3

• Bug Fix
• Fix rest parameter array allocation loop being incorrectly aliased.

5.6.2

• Bug Fix
• Fix method key literals not turning into computed member expression in loose mode.
• Elect rest parameters in spread element position as candidates instead of replacing them in place.

5.6.0

• Bug Fix
• Fix istanbul interop for register hook when registering for non-existence extension.
• Fix super class constructor call differing for no constructor in derived classes.
• Disable module import receiver when in loose mode.
• Fix duplicate filenames when using babel CLI when passing multiple matching patterns.
• Register labels as bindings to fix undeclared variable checks.
• Polish
• Remove unnecessary string binary expressions when transforming template literals.
• Support module live bindings in arbitary positions not in Program statement position.
• Throw error when attemping to replace a Program root node with another node not of type Program.
• Optimise rest parameters in spread element position and allocate rest array at the earliest common ancestor of all references.
• Generate original number representation when value was not changed.
• Check for invalid binding identifiers when generating inferred method names.
• Don't terminate CLI when watching files fail compilation on init.
• New Feature
• Add new plugin API.
• Internal
• Split react displayName addition into a plugin.
• Add check for JSXMemberExpression to t.isReferenced.
• Move validation.undeclaredVariableCheck transformer up.
• Start great core-to-plugin exodus.
• Add BindingIdentifier virtual type.
• Hidden class optimisations.
• Array allocation optimisations.
• Update regenerator.
• Update js-tokens.
• Sync with upstream Acorn.

5.5.8

• Internal
• Remove extremely unprofessional and harsh error message for those hotlinking to resolve-rc.

5.5.7

• Bug Fix
• Push newline after decorators when doing code gen.
• Rewriting error handling to normalise options before merging them.
• Remove duplicate keys in alias-keys.json causing errors in strict mode.
• Fix $ babel --help not showing optional transformers as such.
• New Feature
• Add auxiliaryCommentBefore and auxiliaryCommentAfter options.

5.5.6

• Bug Fix
• Fix let binding collision in loop head not properly replacing AssignmentExpressions.

5.5.5

• Bug Fix
• Fix file.opts not being set before file.log.deprecate was called causing a ReferenceError as it was checking for a property on it.

5.5.4

• Bug Fix
• Add back missing shouldIgnore check.
• Log message on deprecated options rather than throw an error.
• Fix name of auxiliaryComment option when attempting Istanbul interop in babel/register.

5.5.3

• Bug Fix
• Fix weird state bug when traversing overa node ClassProperty instead of path in the es6.classes transformer.

5.5.2

• Bug Fix
• Fix NodePath#isPure on Property nodes.
• Use cwd instead of entry file directory when working out relative directory for babel/register.
• Internal
• Add scary warning for those few who choose to use the WIP experimental transformers.

5.5.1

• Bug Fix
• Remove ClassProperty nodes always in the Flow transformer. This is fine now since class properties aren't supported in any engine that supports classes but the es7.classProperties transformer will need to be updated in the future to desugar to ES6 classes instead of relying on the es6.classes transformer from being ran.

5.5.0

• Bug Fix
• Allow pushing declarations to SwitchStatements.
• Fix minification.removeDebugger to remove DebuggerStatements rather than ExpressionStatements with an identifier of debugger.
• Check LHS in ForInStatement and ForOfStatement for constant violations.
• Register function id as a reference when naming methods to avoid collisions.
• Support key literals when checking for the existence of displayName property when attempting to add it for React.createClass.
• Remove ExportDefaultSpecifier check from t.isDefaultSpecifier.
• Don't consider JSXIdentifier HTML tag identifiers to be references.
• Polish
• Update minification.deadCodeElimination transformer to remove all statements after completion statements.
• Update minification.deadCodeElimination transformer to not inline single used bindings that exist in different scopes.
• When performing Istanbul interop in babel/register, add the auxiliary comment "istanbul ignore text" to get more accurate coverage.
• Add --nolazy argument to babel-node.
• Add support for cluster forking.
• Perform scope tracking in a single pass instead of multiple.
• Smarten up type inferrence and resolution to support the whole array of language constructs.
• Optimise module metadata retrieval into a single pass.
• Ignore trailing commas when inferring newlines.
• Rename minification.inlineExpressions transformer to minification.constantFolding.
• Check path relative to entry file when checking to see if we're inside node_modules when using babel/register.
• Upgrade regenerator.

5.4.7

• Bug Fix
• Don't consider JSXAttribute names to be valid ReferencedIdentifiers.

5.4.6

• Bug Fix
• Fix spec.functionName transformer incorrectly attempting to rename a binding that doesn't exist as it's a global.
• Internal
• Deprecate custom module formatters.

5.4.5

• Bug Fix
• Add JSXIdentifier as a valid ReferencedIdentifier visitor virtual type.
• Ignore CallExpression _prettyCall when the retainLines option is enabled.
• Inherit comments to new declaration node when exploding module declarations.
• Fix es6.tailCall transformer failing on calls that exceed the max parameters of the function.

5.4.4

• Bug Fix
• Fix bug where replacing variable declarations in the head of a for loop would turn them into ExpressionStatements.
• Fix renaming of assignment expressions that were non-identifiers ie. patterns.
• Force space before class id to avoid breaking named classes when using compact mode.
• Add assignment pattern explosion to avoid initial duplicate nodes.
• Ignore this and arguments when performing TCO on shadowed functions.
• Polish
• Rename sourceMapName option to sourceMapTarget. Thanks @getify!
• Better detection of completion records, ignore those in Functions.
• Clarified descriptions of the options that are enabled by default.
• Resolve \babel-plugin-${name}`plugin names **before** just checking thename`. Thanks @jquense!
• Update AMD module formatter to add import default remapping.

5.4.3

• Bug Fix
• Fix module being incorrectly rewritten when used as in an export declaration.
• When performing single-reference inlining, ensure that the single reference isn't a child of the binding itself.
• Fix a bug in minification.deadCodeElimination where a new binding instance was being created for local class bindings instead of just inheriting the parent one.
• Fix bug with paren printing in compact and retainLines mode where a left paren was already printed before catching up.
• Internal
• Handle contexts for paths much better. This will ensure that the path node location info is in sync.

5.4.2

• Polish
• ignore and only patterns are now very liberal. The pattern can now exist anywhere in the path.

5.4.1

• Bug Fix
• Add missing slash dependency. Thanks @browncolyn!
• Polish
• Clean up shouldIgnore algorithm to work how you'd expect rather than being a hacky piece of shit. It now crawls the entire path, checking each section of it against the input ignore/only patterns. This means that the pattern foo will ignore the paths foo/bar.js, bar/foo etc.

5.4.0

• New Feature
• Added function bind syntax behind stage 0. Thanks @RReverser!
• Added env option. Especially handy when using the .babelrc.
• Bug Fix
• Fix files not properly being ignored when babel.transform ignores them when using $ babel.
• Fix scope tracking registering loop head bindings to their VariableDeclaration instead of VariableDeclarator.
• Polish
• Normalise path separators for souce map paths when using $ babel.
• Rework PathHoister to ignore global references and to not deopt on reassignments to referenced bindings, instead it tries to hoist to the highest scope.
• Added missing exponential operator inlining. Thanks @nkt!
• Optimise regenerator transformer. Thanks @benjamn!

5.3.3

• Bug Fix
• Fix minification.deadCodeElimination transformer incorrectly trying to inline import declarations.
• Fix minification.inlineExpression transformer getting into an infinite loop.

5.3.2

• Bug Fix
• Fix patterns not being considered when hoisting variables in the es6.blockScoping transformer.

5.3.1

• Bug Fix
• Fix unique export specifiers not being cloned when exploding class and function exports,
• Polish
• Turn import remaps to sequence expressions to remove their context and improve performance.

5.3.0

Speeeeeeed

• Spec Compliancy
• Allow trailing param commas for methods when using the es7.trailingCommas transformer.
• Bug Fix
• Fix es6.blockScoping transformer not properly ignoring break in SwitchCase.
• Fix lookahead context saving to avoid weird tokenizer state.
• Explode duplicate identifiers in export/import specifiers and property shorthand to create unique objects.
• Skip loose mode for class methods when they have decorators.
• When removing nodes, share their comments with their siblings.
• Properly hoist temp param declarations when doing TCO.
• Internal
• Add --harmony_generators flag to $ babel-node.
• Internal AST traversals have been minimised drastically. Transformers have been grouped together which means entire tree traversals are much fewer. Visiting nodes is now also skipped if the traversal context can detect that the handler is a noop. This sames precious cycles as it avoids constructing traversal paths and creating a new traversal context. See issues #1472 and #1486 for related discussion.
• Polish
• Move many utility transformers to minification.

5.2.17

• Bug Fix
• Fix auxiliary comments not properly being attached to function declaration helpers.
• Add Super node type to ast-types patch.
• Ignore parameter bindings when attempting to inline them in the minification.deadCodeElimination transformer.
• Correct extensions arguments when using the Babel CLI.

5.2.16

• Bug Fix
• Fix plugins being disabled when using the whitelist.
• Fix correct function scope being passed to nameMethod.property when inferring the function name for class methods.
• Fix incorrect extensions reference causing weird issues when using the Babel CLI.
• Fix destructuring param reference replacements not inheriting from their original param.
• Spec Compliancy
• Fix order that method decorators are ran in.

5.2.15

• Bug Fix
• Fix initializer descriptor add attempt if it doesn't exist.

5.2.14

• Bug Fix
• Fix bug with initializer decorators where the descriptors weren't being defined if there was no initializer property.
• Internal
• Expose retainLines option to CLI.
• Fix retainLines option not being taken into consideration when doing multiple variable declaration declarators generation.
• Expose minified and unminified copies of dist scripts.

5.2.13

• Bug Fix
• Fix ExportDeclarations being incorrectly removed when using the utility.deadCodeElimination transformer.
• Fix position of utility transformers.
• New Feature
• Add built-in esquery support.
• Internal
• Consolidate notion of "virtual types".

5.2.12

• Polish
• Make UID generation based on module declarations much nicer.
• Internal
• Remove internal check for traversal path replacement of self. This is a pattern that could come up in the wild and it could lead to pretty nasty code and may lead to internal regressions as the test coverage isn't 100% :( Instead, just put it in the fast path.

5.2.11

• Internal
• Rename getModuleName option to getModuleId, doh.

5.2.10

• Bug Fix
• Fix numerous issues in replaceWithSourceString. Thanks @pangratz!
• New Feature
• Add getModuleName option. Thanks @jayphelps!

5.2.9

• Bug Fix
• Fix _blockHoist transformer incorrectly sorting nodes on shitty environments that aren't spec compliant in their key order.
• Fix broken parse API method reference to an undeclared import.

5.2.7

• Bug Fix
• Move utility.deadCodeElimination transformer up to avoid race conditions.
• Fix shorthand property scope binding renaming.
• Polish
• Turn helper variable declarations into function declarations if possible.
• Internal
• Removed native inheritance support from classes.
• Added replaceWithSourceString path API.
• Split up es3.propertyLiterals and es3.memberExpressionLiterals transformers to minfication.propertyLiterals and es3.memberExpressionLiterals.

5.2.6

• Internal
• Fix transformer aliases being accidently set as deprecated ones.
• Expose Pipeline as TransformerPipeline instead.

5.2.5

• Bug Fix
• Fix parse API not adding all the correct pipeline transformers.

5.2.4

• Bug Fix
• Fix race condition with the Node API being loaded awkwardly and not being able to initialise itself when used in the browser.
• Internal
• Expose transform.pipeline.

5.2.3

• Bug Fix
• Fix plugin containers being called with an undefined import. Thanks @timbur!
• Allow Flow object separators to be commas. Thanks @monsanto!
• Add missing Statement and Declaration node aliases to flow types.

5.2.2

• Internal
• Allow util.arrayify to take arbitrary types and coerce it into an array.

5.2.1

• Bug Fix
• Fix regression in node/register that caused node_modules to not be ignored.

5.2.0

• Bug Fix
• Fix plugin strings splitting arbitrarily on : which caused full paths on Windows to fail as they include : after the drive letter.
• Call class property initializers with their target instead of their descriptor.
• Fix ignore and only not properly working on Windows path separators. Thanks @stagas!
• Fix resolveRc running on files twice causing issues. Thanks @lukescott!
• Fix shorthand properties not correctly being target for isReferenced checks. Thanks @monsanto!
• Polish
• Allow passing an array of globs to babel/register only and ignore options. Thanks @Mark-Simulacrum!
• When inferring function names that collide with upper bindings, instead of doing the wrapper, instead rename them.
• Consider constant-like variable declaration functions to always refer to themselves so TOC can be performed.
• Process globs manually when using $ babel as some shells such as Windows don't explode them. Thanks @jden!
• Add alternative way to execute plugins via a closure that's called with the current Babel instance.
• Internal
• Remove multiple internal transformers in favor of directly doing things when we need to. Previously, declarations such as _ref that we needed to create in specific scopes were done at the very end via the _declarations transformer. Now, they're done and added to the scope right when they're needed. This gets rid of the crappy _declarations property on scope nodes and fixes the crappy regenerator bug where it was creating a new BlockStatement so the declarations were being lost.
• Rework transformer traversal optimisation. Turns out that calling a check function for every single node in the AST is ridiculously expensive. 300,000 nodes timesed by ~30 transformers meant that it took tens of seconds to perform while it's quicker to just do the unnecessary traversal. Seems obvious in hindsight.
• New Feature
• Add jscript transformer that turns named function expressions into function declarations to get around JScript's horribly broken function expression semantics. Thanks @kondi!
• Add @@hasInstance support to objects when using the es6.spec.symbols transformer.
• Add retainLines option that retains the line (but not the columns!) of the input code.

5.1.13

• Polish
• Remove symbol check from defineProperty helper.

5.1.12

• Bug Fix
• Fix resolveModuleSource not being ran on ExportAllDeclarations.
• Fix .babelrc being resolved multiple times when using the require hook.
• Fix parse error on spread properties in assignment position.
• Fix externalHelpers option being incorrectly listed as type string.
• Internal
• Upgrade core-js to 0.9.0.
• Spec Compliancy
• Fix object decorators not using the initializer pattern.
• Remove property initializer descriptor reflection.

5.1.11

• Bug Fix
• Memoise and bind member expression decorators.
• Move JSX children cleaning to opening element visitor. Fixes elements not being cleaned in certain scenarios.
• Consider SwitchStatements to be Scopable.
• Fix bluebirdCoroutines calling interopRequireWildcard before it's defined.
• Add space to do...while code generation.
• Validate super use before this on super exit rather than entrance.
• Polish
• Add Babel name to logger.

5.1.10

• Bug Fix
• Remove makePredicate from acorn in favor of an indexOf.
• Remove statements to expression explosion when inserting a block statement.
• Internal
• Remove runtime compatibility check.

5.1.9

• Bug Fix
• Fix class property initializers with undefined values not being correctly writable.
• Fix self inferring generators incorrectly causing a stack error.
• Fix default export specifiers not triggering AMD module argument inclusion.
• Fix assignments not having their module references properly remapped.
• Internal
• Upgrade to latest acorn.
• Polish
• Make invalid LHS pattern error messages nicer.

5.1.8

• Bug Fix
• Only make parenthesized object pattern LHS illegal.

5.1.7

• Internal
• Add parse node API.

5.1.6

• Bug Fix
• Fix runtime built-in catchall not properly checking for local variables.

5.1.5

• Internal
• Bump core-js version.

5.1.4

• Polish
• Add missing Reflect methods to runtime transformer.

5.1.3

• Internal
• Switch entirely to vanilla regenerator.
• Clean up and make the parsing of decorators stateless.
• Bug Fix
• Don't do TCO on generators and async functions.
• Add missing core-js runtime definitions.

5.1.2

• Bug Fix
• Add getIterator and isIterable to babel-runtime build script.

5.1.1

• Bug Fix
• Add missing runtime symbol definitions.

5.1.0

• Bug Fix
• Fix super reference when using decorators.
• Don't do array unpack optimisation when member expressions are present.
• Add missing descriptors for undecorated class properties.
• Don't consider arguments and eval valid function names when doing function name inferrence.
• Fix scope tracking of constants in loop heads.
• Parse AwaitExpression as a unary instead of an assignment.
• Fix regex evaluation when attempting static evaluation.
• Don't emit tokens when doing a lookahead.
• Add missing test declaration to utility.deadCodeElimination transformer.
• Internal
• Upgrade regenerator to the latest and use my branch with the hope of eventually switching to vanilla regenerator.
• Add support for the replacement of for loop inits with statements.
• Upgrade dependencies.
• Polish
• When adding the scope IIFE when using default parameters, don't shadow the function expression, just apply this and arguments if necessary.
• Use path basename as non-default import fallback.
• New Feature
• Add trailing function comma proposal. Thanks @AluisioASG!
• Add support for object literal decorators.
• Make core-js modular when using the runtime transformer.

5.0.12

• Bug Fix
• Fix incorrect remapping of module references inside of a function id redirection container.

5.0.11

• Bug Fix
• Fix new for...of loops not properly inheriting their original loop.
• Internal
• Disable scope instance cache.
• Polish
• Allow comments in .babelrc JSON.

5.0.9

• Polish
• Use moduleId for UMD global name if available.
• Bug Fix
• Fix UMD global module variable shadowing the amd/common module variable.
• Fix Flow param type annotation regression.
• Fix function name collision toString wrapper. Thanks @alawatthe!

5.0.8

• Bug Fix
• Fix falsy static class properties not being writable.
• Fix block scoping collisions not properly detecting modules and function clashes.
• Skip this before super for derived constructors on functions.

5.0.7

• New Feature
• Add --ignore and --only support to the CLI.
• Bug Fix
• Remove HOMEPATH environment variable from home resolution in babel/register cache.
• Internal
• Disable WIP path resolution introducing infinite recursion in some code examples.
• Polish
• Add live binding to CommonJS default imports.

5.0.6

• Bug Fix
• Fix mangling of import references that collide with properties on Object.prototype.
• Fix duplicate declarations incorrectly being reported for var.

5.0.5

• Internal
• Upgrade core-js.
• Bug Fix
• Fix arrays not being supported in util.list.

5.0.4

• Polish
• Check for top level breakConfig in resolveRc.

5.0.3

• Bug Fix
• Make relative location absolute before calling resolveRc.
• Internal
• Switch to global UID registry.
• Add breakConfig option to prevent Babel from erroring when hitting that option.

5.0.1

• Bug Fix
• Fix duplicate declaration regression.
• Fix not being able to call non-writable methods.

5.0.0

• New Feature
• Decorators based on @wycat's stage 1 proposal.
• Class property initializers based on @jeffmo's stage 0 proposal.
• Export extensions based on @leebyron's stage 1 proposal.
• UMD module formatter now supports globals.
• Add es3.runtime, optimisation.react.inlineElements and optimisation.react.constantElements transformers.
• Add stage option that replaces the experimental one.
• Allow ES7 transformer to be enabled via optional instead of only via stage.
• Infer string quotes to use in the code generator.
• Consider export { foo as default }; to be the same as export default foo;.
• Add nonStandard option that can be set to false to remove parser support for JSX and Flow.
• Add jsxPragma option.
• Automatically generate CLI options based on internal API options.
• Add support for .babelrc on absolute paths.
• Plugin API!
• Internal
• Export options in browser API.
• Rewritten parser.
• Don't block hoist when runtime transformer is enabled in system module formatter.
• Rewritten the internal traversal and node replacement API to use "paths" that abstracts out node relationships.
• Polish
• JSX output is now more inline with the official JSX transformer.
• Hoist block scoping IIFE - this improves memory usage and performance.
• Better IIFE detection - references are now checked to see if they're referencing the binding we're searching for.
• Check for import reassignments in constants transformer.
• Make method definitions with expression bodies illegal.
• Save register cache on tick instead of SIGINT.
• Enable strict mode on babel-node eval flag.
• Bug Fixes
• Add support for live bindings. This change also increases the reliablity of export specifier renaming.
• Add support for super update and non equals assignment expressions.
• Rename shadow constructor binding in classes.
• Seed next iteration bindings with previous fresh bindings when reassinging loop block scoped variables.
• Fix new expression spread referencing the wrong constructor.
• Call resolveModuleSource on dynamic imports.
• Added param to list of duplicate declaration kinds.
• Breaking Changes
• The Babel playground has been removed.
• ES7 Abstract References have been removed.
• Experimental option has been removed in favor of a stage option.
• Rename returnUsedHelpers to metadataUsedHelpers.

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!

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 breaks 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!
• Bug Fix
• Fix node duplication sometimes resulting in a recursion error.
• Ignore breaks 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 Compliancy
• 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 proplery 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 Compliancy
• for...of now outputs in a lengthy try...catch this is to ensure spec compliancy in regards to iterator returns and abrupt completions. See google/traceur-compiler#1773 and babel/babel/#838 for more information.
• Polish
• Rest parameters that are only refered to via number properties on member expressions are desugared into a direct arguments reference. Thanks @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!
• 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!
• 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!
• 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!

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".