b85d6c7e4a
This syntax allows you to specify whether a type variable can appear in a covariant or contravariant position, and is super useful for, say, Promise. Right now this is hacked in jankily, but in the next major release we should stop using Identifier nodes for type parameters.
Babylon is a JavaScript parser used in Babel.
- ES6 enabled by default.
- Comment attachment.
- Support for JSX and Flow.
- Support for experimental language proposals.
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, interspacial 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". -
plugins: Array containing the plugins that you want to enable.
Example
require("babylon").parse("code", {
// parse in strict mode and allow module declarations
sourceType: "module",
plugins: [
// enable experimental async functions
"asyncFunctions",
// enable jsx and flow syntax
"jsx",
"flow"
]
});
Plugins
jsxflowasyncFunctionsclassConstructorCalldoExpressionstrailingFunctionCommasobjectRestSpreaddecoratorsclassPropertiesexportExtensionsexponentiationOperatorasyncGeneratorsfunctionBindfunctionSent