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).