estree-to-babel

What is estree-to-babel?

The estree-to-babel npm package is a utility that converts ESTree-compatible AST (Abstract Syntax Tree) into a format that is compatible with Babel. This is particularly useful for developers working on tools that manipulate JavaScript code, such as compilers or code formatters, where they need to integrate with Babel's ecosystem.

What are estree-to-babel's main functionalities?

Convert ESTree AST to Babel-compatible AST

This feature allows the conversion of an AST in ESTree format to a Babel-compatible format. The code sample demonstrates how to convert a simple ESTree AST representing the number 42 into a Babel AST.

const estreeToBabel = require('estree-to-babel');
const estreeAst = {
  type: 'Program',
  body: [{
    type: 'ExpressionStatement',
    expression: {
      type: 'Literal',
      value: 42,
      raw: '42'
    }
  }]
};
const babelAst = estreeToBabel(estreeAst);
console.log(babelAst);

Other packages similar to estree-to-babel

babel-types

This package contains all of the Babel types constructors used for creating ASTs. It is similar to estree-to-babel in that it deals with AST manipulations, but it is more about creation rather than conversion.

recast

Recast provides the ability to parse JavaScript code, manipulate the resulting AST, and generate new code. It uses a different AST format by default but can be configured to use the ESTree format, making it somewhat similar to estree-to-babel in terms of manipulating ASTs but with broader functionality including parsing and code generation.

README

Estree-to-babel

Convert ESTree-compatible JavaScript AST to Babel AST.

To use parsers like:

• acorn
• cherow
• espree
• etc...

With babel tools like:

• @babel/traverse
• @babel/types
• etc...

The thing is @babel/parser has a little differences 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;
• etc...

Also @babel/parser has differences with 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;
• etc...

estree-to-babel aims to smooth this differences.

Install

npm i estree-to-babel

Example

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';
    },
});

License

MIT