Swc-to-babel NPM

SWC-to-babel

Convert SWC JavaScript AST to Babel AST.

To use SWC parser with babel tools like:

The thing is @babel/parser has a a little differences with swc standard:

File node exists;
Program instead of Module;
loc with line and column instead of span;
StringLiteral has no kind an hasEscape;
Identifier has no optional and uses name instead of value;
BlockStatement has body instead of stmts;
VariableDeclarator has no optional and definite;
CallExpression has no typeArguments, spread and expression properties in arguments;
TemplateElement has value field with raw and cooked;
TypeScript ast nodes has prefix TS instead of Ts;
ExportNamedDeclaration instead of ExportDeclaration;
ExportDefaultDeclaration instead of ExportDefaultExpression;
VariableDeclaration has no declare field;
Has no ParenthesisExpression;
ClassDeclaration and ClassExpression uses id instead of identifier, has ClassBody;
ClassMethod uses static instead of isStatic;
MemberExpression has computed property instead of Computed node in property field;
NewExpression has no untyped node with a spread property in arguments, always has arguments field, instead of null when absent;
ArrayExpression has no untyped node with a spread property in elements;
Function has no typeParameters;
TSTypeReference has no typeParams field;
TSTypeOperator has operator instead of op;
TSTypeParameter has a field name which is string instead of Identifier;
FunctionDeclaration instead of FunctionExpression with identifier field;
ImportDeclaration has importKind instead of typeOnly and attributes fields;
ObjectProperty instead of KeyValueProperty, KeyValuePatternProperty and AssignmentPatternProperty;
ExportNamedDeclaration has exportKind, specifiers fields;
ExportSpecifier has local which is never null instead of orig;
ExportDefaultDeclaration has declaration instead of decl;
TSAnyKeyword instead of TSKeywordType;
TSAsExpression instead of TsConstAssertion;
ObjectMethod with kind: get instead of GetterProperty
ObjectMethod with kind: set instead of SetterProperty
etc...

swc-to-babel aims to smooth this differences.

Install

npm i swc-to-babel

Example

const swc = require('@swc/core');
const toBabel = require('swc-to-babel');
const traverse = require('@babel/traverse').default;

const ast = toBabel(swc.parseSync(`
    const f = ({a}) => a;
`));

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

API reference

/**
 * Convert an SWC ast to a babel ast
 * @param ast {Module} SWC ast
 * @param {string} [src=""] Source code
 * @returns {ParseResult<File>} Babel ast
 */
export default function toBabel(ast: Module, src?: string): ParseResult<File>;