3.3.0 (2016-07-25)
Bug fixes
Fix bug in tokenizing of regexp operator after a function declaration.
Fix parser crash when parsing an array pattern with a hole.
New features
Implement check against complex argument lists in functions that enable strict mode in ES7.
3.2.0 (2016-06-07)
Bug fixes
Improve handling of lack of unicode regexp support in host environment.
Properly reject shorthand properties whose name is a keyword.
Don't crash when the loose parser is called without options object.
New features
Visitors created with visit.make now have their base as prototype,
rather than copying properties into a fresh object.
Make it possible to use visit.ancestor with a walk state.
3.1.0 (2016-04-18)
Bug fixes
Fix issue where the loose parser created invalid TemplateElement nodes for unclosed template literals.
Properly tokenize the division operator directly after a function expression.
Allow trailing comma in destructuring arrays.
New features
The walker now allows defining handlers for CatchClause nodes.
3.0.4 (2016-02-25)
Fixes
Allow update expressions as left-hand-side of the ES7 exponential operator.
3.0.2 (2016-02-10)
Fixes
Fix bug that accidentally made undefined a reserved word when
parsing ES7.
3.0.0 (2016-02-10)
Breaking changes
The default value of the ecmaVersion option is now 6 (used to be 5).
Support for comprehension syntax (which was dropped from the draft spec) has been removed.
Fixes
let and yield are now “contextual keywords”, meaning you can
mostly use them as identifiers in ES5 non-strict code.
A parenthesized class or function expression after export default is
now parsed correctly.
New features
When ecmaVersion is set to 7, Acorn will parse the exponentiation
operator (**).
The identifier character ranges are now based on Unicode 8.0.0.
Plugins can now override the raiseRecoverable method to override the
way non-critical errors are handled.
2.7.0 (2016-01-04)
Fixes
Stop allowing rest parameters in setters.
Make sure the loose parser always attaches a local property to
ImportNamespaceSpecifier nodes.
Disallow y rexexp flag in ES5.
Disallow \00 and \000 escapes in strict mode.
Raise an error when an import name is a reserved word.
2.6.4 (2015-11-12)
Fixes
Fix crash in loose parser when parsing invalid object pattern.
New features
Support plugins in the loose parser.
2.6.2 (2015-11-10)
Fixes
Don't crash when no options object is passed.
2.6.0 (2015-11-09)
Fixes
Add await as a reserved word in module sources.
Disallow yield in a parameter default value for a generator.
Forbid using a comma after a rest pattern in an array destructuring.
New features
Support parsing stdin in command-line tool.
2.5.2 (2015-10-27)
Fixes
Fix bug where the walker walked an exported let statement as an
expression.
2.5.0 (2015-10-27)
Fixes
Fix tokenizer support in the command-line tool.
In the loose parser, don't allow non-string-literals as import sources.
Stop allowing new.target outside of functions.
Remove legacy guard and guardedHandler properties from try nodes.
Stop allowing multiple __proto__ properties on an object literal in
strict mode.
Don't allow rest parameters to be non-identifier patterns.
Check for duplicate paramter names in arrow functions.