- The latest ECMAScript version enabled by default (ES2017).
- Comment attachment.
- Support for JSX and Flow.
- Support for experimental language proposals (accepting PRs for anything at least stage-0).
Significant diversions are expected to occur in the future such as streaming, EBNF definitions, sweet.js integration, interspatial parsing and more.
parse() parses the provided
code as an entire ECMAScript program, while
parseExpression() tries to parse a single Expression with performance in
mind. When in doubt, use
allowImportExportEverywhere: By default,
exportdeclarations can only appear at a program's top level. Setting this option to
trueallows them anywhere where a statement is allowed.
allowReturnOutsideFunction: By default, a return statement at the top level raises an error. Set this to
trueto accept such code.
sourceType: Indicate the mode the code should be parsed in. Can be either
sourceFilename: Correlate output AST nodes with their source filename. Useful when generating code and source maps from the ASTs of multiple input files.
startLine: By default, the first line of code parsed is treated as line 1. You can provide a line number to alternatively start with. Useful for integration with other source tools.
plugins: Array containing the plugins that you want to enable.
There is now an
estreeplugin which reverts these deviations
- Literal token is replaced with StringLiteral, NumericLiteral, BooleanLiteral, NullLiteral, RegExpLiteral
- Property token is replaced with ObjectProperty and ObjectMethod
- MethodDefinition is replaced with ClassMethod
- Program and BlockStatement contain additional
directivesfield with Directive and DirectiveLiteral
- ClassMethod, ObjectProperty, and ObjectMethod value property's properties in FunctionExpression is coerced/brought into the main method node.
AST for JSX code is based on Facebook JSX AST with the addition of one node type:
Babylon follows semver in most situations. The only thing to note is that some spec-compliancy bug fixes may be released under patch versions.
For example: We push a fix to early error on something like #107 - multiple default exports per file. That would be considered a bug fix even though it would cause a build to fail.
decorators(Based on an outdated version of the Decorators proposal. Will be removed in a future version of