babel-core

Babel compiler core.

var babel = require("babel-core");
import { transform } from 'babel-core';
import * as babel from 'babel-core';

All transformations will use your local configuration files (.babelrc or in package.json). See options to disable it.

babel.transform(code: string, options?: Object)

Transforms the passed in code. Returning an object with the generated code, source map, and AST.

babel.transform(code, options) // => { code, map, ast }

Example

var result = babel.transform("code();", options);
result.code;
result.map;
result.ast;

babel.transformFile(filename: string, options?: Object, callback: Function)

Asynchronously transforms the entire contents of a file.

babel.transformFile(filename, options, callback)

Example

babel.transformFile("filename.js", options, function (err, result) {
  result; // => { code, map, ast }
});

babel.transformFileSync(filename: string, options?: Object)

Synchronous version of babel.transformFile. Returns the transformed contents of the filename.

babel.transformFileSync(filename, options) // => { code, map, ast }

Example

babel.transformFileSync("filename.js", options).code;

babel.transformFromAst(ast: Object, code?: string, options?: Object)

Given, an AST, transform it.

const code = "if (true) return;";
const ast = babylon.parse(code, { allowReturnOutsideFunction: true });
const { code, map, ast } = babel.transformFromAst(ast, code, options);

Options

Babel CLI

You can pass these options from the Babel CLI like so:

babel --name=value

Following is a table of the options you can use:

Option	Default	Description
`ast`	`true`	Include the AST in the returned object
`auxiliaryCommentAfter`	`null`	Attach a comment after all non-user injected code.
`auxiliaryCommentBefore`	`null`	Attach a comment before all non-user injected code.
`babelrc`	`true`	Specify whether or not to use .babelrc and .babelignore files. Not available when using the CLI, use `--no-babelrc` instead.
`code`	`true`	Enable code generation
`comments`	`true`	Output comments in generated output.
`compact`	`"auto"`	Do not include superfluous whitespace characters and line terminators. When set to `"auto"` compact is set to `true` on input sizes of >500KB.
`env`	`{}`	This is an object of keys that represent different environments. For example, you may have: `{ env: { production: { /* specific options */ } } }` which will use those options when the environment variable `BABEL_ENV` is set to `"production"`. If `BABEL_ENV` isn't set then `NODE_ENV` will be used, if it's not set then it defaults to `"development"`
`extends`	`null`	A path to an `.babelrc` file to extend
`filename`	`"unknown"`	Filename for use in errors etc.
`filenameRelative`	`(filename)`	Filename relative to `sourceRoot`.
`generatorOpts`	`{}`	An object containing the options to be passed down to the babel code generator, babel-generator
`getModuleId`	`null`	Specify a custom callback to generate a module id with. Called as `getModuleId(moduleName)`. If falsy value is returned then the generated module id is used.
`highlightCode`	`true`	ANSI highlight syntax error code frames
`ignore`	`null`	Opposite to the `only` option. `ignore` is disregarded if `only` is specified.
`inputSourceMap`	`null`	A source map object that the output source map will be based on.
`minified`	`false`	Should the output be minified (not printing last semicolons in blocks, printing literal string values instead of escaped ones, stripping `()` from `new` when safe)
`moduleId`	`null`	Specify a custom name for module ids.
`moduleIds`	`false`	If truthy, insert an explicit id for modules. By default, all modules are anonymous. (Not available for `common` modules)
`moduleRoot`	`(sourceRoot)`	Optional prefix for the AMD module formatter that will be prepend to the filename on module definitions.
`only`	`null`	A glob, regex, or mixed array of both, matching paths to only compile. Can also be an array of arrays containing paths to explicitly match. When attempting to compile a non-matching file it's returned verbatim.
`parserOpts`	`{}`	An object containing the options to be passed down to the babel parser, babylon
`plugins`	`[]`	List of plugins to load and use.
`presets`	`[]`	List of presets (a set of plugins) to load and use.
`retainLines`	`false`	Retain line numbers. This will lead to wacky code but is handy for scenarios where you can't use source maps. (NOTE: This will not retain the columns)
`resolveModuleSource`	`null`	Resolve a module source ie. `import "SOURCE";` to a custom value. Called as `resolveModuleSource(source, filename)`.
`shouldPrintComment`	`null`	An optional callback that controls whether a comment should be output or not. Called as `shouldPrintComment(commentContents)`. NOTE: This overrides the `comment` option when used.
`sourceFileName`	`(filenameRelative)`	Set `sources[0]` on returned source map.
`sourceMaps`	`false`	If truthy, adds a `map` property to returned output. If set to `"inline"`, a comment with a sourceMappingURL directive is added to the bottom of the returned code. If set to `"both"` then a `map` property is returned as well as a source map comment appended. This does not emit sourcemap files by itself! To have sourcemaps emitted using the CLI, you must pass it the `--source-maps` option.
`sourceMapTarget`	`(filenameRelative)`	Set `file` on returned source map.
`sourceRoot`	`(moduleRoot)`	The root from which all sources are relative.
`sourceType`	`"module"`	Indicate the mode the code should be parsed in. Can be either "script" or "module".
`wrapPluginVisitorMethod`	`null`	An optional callback that can be used to wrap visitor methods. NOTE: This is useful for things like introspection, and not really needed for implementing anything. Called as `wrapPluginVisitorMethod(pluginAlias, visitorType, callback)`.