babel-core

babel-core

Babel compiler core.

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

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
filename	"unknown"	Filename for use in errors etc.
filenameRelative	(filename)	Filename relative to sourceRoot.
presets	[]	List of presets (a set of plugins) to load and use.
plugins	[]	List of plugins to load and use.
parserOpts	{}	An object containing the options to be passed down to the babel parser, babylon
generatorOpts	{}	An object containing the options to be passed down to the babel code generator, babel-generator
highlightCode	true	ANSI highlight syntax error code frames
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.
ignore	null	Opposite to the only option. ignore is disregarded if only is specified.
auxiliaryCommentBefore	null	Attach a comment before all non-user injected code.
auxiliaryCommentAfter	null	Attach a comment after all non-user injected code.
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.
inputSourceMap	null	A source map object that the output source map will be based on.
sourceMapTarget	(filenameRelative)	Set file on returned source map.
sourceFileName	(filenameRelative)	Set sources[0] on returned source map.
sourceRoot	(moduleRoot)	The root from which all sources are relative.
moduleRoot	(sourceRoot)	Optional prefix for the AMD module formatter that will be prepend to the filename on module definitions.
moduleIds	false	If truthy, insert an explicit id for modules. By default, all modules are anonymous. (Not available for common modules)
moduleId	null	Specify a custom name for module ids.
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.
resolveModuleSource	null	Resolve a module source ie. import "SOURCE"; to a custom value. Called as resolveModuleSource(source, filename).
code	true	Enable code generation
no-babelrc	CLI flag	Specify whether or not to use .babelrc and .babelignore files. Only available when using the CLI.
ast	true	Include the AST in the returned object
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.
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)
comments	true	Output comments in generated output.
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.
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 enviroment 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"
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)
extends	null	A path to an .babelrc file to extend