7c18bf83cc
* Increase test coverage * Test for error when binding `this` in destructuring pattern * Ignore coverage of inAsync check in parseAwait - already checked externally * Ignore coverage of default case in checkPropClash * Remove unused parameter isAsync from parseParenAndDistinguishExpression * Ignore coverage of an `else` branch in flowParseTypeParameterDeclaration * Flow: remove unused parameters to flowParseTypeAnnotatableIdentifier * Flow: ignore coverage of pass-through throw statement in parseConditional * Flow: Add test for error on property with type param * Flow: ignore coverage of pass-through throw statements in parseMaybeAssign, parseArrow * Add test for error on XML-style comment in module code * Update test for error on method in object pattern * Test for error: "Only '=' operator can be used for specifying default value"
Babylon is a JavaScript parser used in Babel.
- 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.
Credits
Heavily based on acorn and acorn-jsx, thanks to the awesome work of @RReverser and @marijnh.
Significant diversions are expected to occur in the future such as streaming, EBNF definitions, sweet.js integration, interspatial parsing and more.
API
babylon.parse(code, [options])
Options
-
allowImportExportEverywhere: By default,
importandexportdeclarations can only appear at a program's top level. Setting this option totrueallows 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. -
allowSuperOutsideMethod TODO
-
sourceType: Indicate the mode the code should be parsed in. Can be either
"script"or"module". -
sourceFilename: Correlate output AST nodes with their source filename. Useful when generating code and source maps from the ASTs of multiple input files.
-
plugins: Array containing the plugins that you want to enable.
Output
Babylon generates AST according to Babel AST format. It is based on ESTree spec with the following 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:
JSXText
Semver
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.
Example
require("babylon").parse("code", {
// parse in strict mode and allow module declarations
sourceType: "module",
plugins: [
// enable jsx and flow syntax
"jsx",
"flow"
]
});
Plugins
jsxflowdoExpressionsobjectRestSpreaddecoratorsclassPropertiesexportExtensionsasyncGeneratorsfunctionBindfunctionSentdynamicImport