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# babel-core
> Babel compiler core.
```javascript
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](#options) to disable it.
## babel.transform(code: string, [options?](#options): Object)
Transforms the passed in `code`. Returning an object with the generated code,
source map, and AST.
```js
babel.transform(code, options) // => { code, map, ast }
```
**Example**
```js
var result = babel.transform("code();", options);
result.code;
result.map;
result.ast;
```
## babel.transformFile(filename: string, [options?](#options): Object, callback: Function)
Asynchronously transforms the entire contents of a file.
```js
babel.transformFile(filename, options, callback)
```
**Example**
```js
babel.transformFile("filename.js", options, function (err, result) {
result; // => { code, map, ast }
});
```
## babel.transformFileSync(filename: string, [options?](#options): Object)
Synchronous version of `babel.transformFile`. Returns the transformed contents of
the `filename`.
```js
babel.transformFileSync(filename, options) // => { code, map, ast }
```
**Example**
```js
babel.transformFileSync("filename.js", options).code;
```
## babel.transformFromAst(ast: Object, code?: string, [options?](#options): Object)
Given, an [AST](https://astexplorer.net/), transform it.
```js
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](https://babeljs.io/docs/en/babel-cli#ignoring-babelrc). |
| `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](https://github.com/isaacs/minimatch), 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](https://babeljs.io/docs/en/plugins) to load and use. |
| `presets` | `[]` | List of [presets](https://babeljs.io/docs/en/plugins#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)`.
|
