estree-to-babel/README.md

convert estree ast to babel

# Estree-to-babel [![NPM version][NPMIMGURL]][NPMURL] [![Build Status][BuildStatusIMGURL]][BuildStatusURL] [![Coverage Status][CoverageIMGURL]][CoverageURL]

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Convert [`ESTree`](https://github.com/estree/estree)-compatible `JavaScript AST` to [`Babel AST`](https://github.com/babel/babel/blob/main/packages/babel-parser/ast/spec.md).

To use parsers like:

- [`acorn`](https://github.com/acornjs/acorn)
- [`cherow`](https://github.com/cherow/cherow)
- [`espree`](https://github.com/eslint/espree)
- etc...

With `babel` tools like:

- [`@babel/traverse`](https://babeljs.io/docs/en/babel-traverse)
- [`@babel/types`](https://babeljs.io/docs/en/babel-types)
- etc...

The thing is [`@babel/parser`](https://babeljs.io/docs/en/babel-parser) has a [little differences](https://babeljs.io/docs/en/babel-parser#output) with `estree` standard:

- `Property` of `ObjectExpression` and `ObjectPattern` called `ObjectProperty`;
- `FunctionExpression` of a `Property` located in `ObjectMethod` node;
- `File` node;
- `StringLiteral`, `NumericLiteral`, `NullLiteral`, `RegExpLiteral`, `BooleanLiteral` instead of `Literal`;
- `ClassMethod` instead of `MethodDefinition`;
- `ClassPrivateMethod`;
- `ClassPrivateName` stores name as `Identifier` in `id` field;
- `ClassPrivateProperty` instead of `FieldDefinition`;
- `OptionalMemberExpression` and `OptionalCallExpression` instead of `ChainExpression`;
- `ImportDeclaration` and `ExportNamedDeclaration` has `attributes`;
- `JSXText` has `extra` field;
- `extra.parenthesized=true` instead of `ParenthesizedExpression`;
- etc...

Also [`@babel/parser`](https://babeljs.io/docs/en/babel-parser) has differences with [`typescript-estree`](https://github.com/typescript-eslint/typescript-eslint/tree/main/packages/typescript-estree):

- `ClassPrivateProperty` instead of `PropertyDefinition` when `key.type=PrivateName`;
- `ClasseProperty` instead of `PropertyDefinition` when `key.type=Identifier`;
- `PrivateName` instead of `PrivateIdentifier`;
- `TSQualifiedName` instead of `MemberExpression`  in `TSInterfaceHeritage`;
- `TSDeclaredMethod` with `abstract=true` instead of `TSAbstractMethodDefinition`;
- `extra.parenthesized=true` instead of `TSParenthesizedType`;
- etc...

`estree-to-babel` aims to smooth this differences.

## Install

```
npm i estree-to-babel
```

### Example

```js
const cherow = require('cherow');
const toBabel = require('estree-to-babel');
const traverse = require('@babel/traverse').default;

const ast = toBabel(cherow.parse(`
    const f = ({a}) => a;
`));

traverse({
    ObjectProperty(path) {
        console.log(path.value.name);
        // output
        'a';
    },
});
```

You can provide options:

```js
import * as cherow from 'cherow';
import {estreeToBabel} from 'estree-to-babel';
import traverse from '@babel/traverse';

const options = {
    convertParens: false,
};

const ast = estreeToBabel(cherow.parse(`
    (a = b)
`), options);

traverse({
    AssignmentExpression(path) {
        console.log(path.parentPath.type);
        // output
        'ParenthesizedExpression';
    },
});
```

## License

MIT