Recast Babel TS Helper

This is a package that helps you to select nodes when working with extensions in VS Code and Recast.

Basic usage may look like this:

Install:

npm install recast-babel-ts-helper

Usage:

To see a bit of what you can do, visit the examples in /examples/examples.test.ts. Run the tests with the npm run test-examples.

What and why is this?

I'm created this library because I am working with VS Code extensions and I kept writing clunky code to locate nodes with full type safety.

Typical usage

A standard usage case could be to rename a function in your code. In the following example we want to rename "myFunction" to "yourFunction":

import {
  generateAstFromCode,
  generateCodeFromAST,
  getTypeSafeNode,
  isOfNodeType,
} from "recast-babel-ts-helper";
import { ExportNamedDeclaration, VariableDeclaration } from "@babel/types";

const code = `export const myFunction = (a: number, b: number): number => a + b;`;
const ast = generateAstFromCode(code);

const baseNode = ast.program.body[0];

const exportNamedDeclarationNode = getTypeSafeNode<ExportNamedDeclaration>(
  baseNode,
  "ExportNamedDeclaration"
);

if (
  isOfNodeType<VariableDeclaration>(
    exportNamedDeclarationNode.declaration,
    "VariableDeclaration"
  )
) {
  const variableDeclaration = getTypeSafeNode<VariableDeclaration>(
    exportNamedDeclarationNode.declaration,
    "VariableDeclaration"
  );
  if ("name" in variableDeclaration.declarations[0].id) {
    variableDeclaration.declarations[0].id.name = "yourFunction";
  }
}

const newCode = generateCodeFromAST(ast);

console.log(newCode);

// export const yourFunction = (a: number, b: number): number => a + b;

Another case can be when you want to examine name och parameters for a piece of code:

import { parseFunctionOrClass } from "recast-babel-ts-helper";

const exampleCode = "export const makeStatement = () => 'hello world';";
const results = parseFunctionOrClass(exampleCode);

expect(results).toHaveLength(1);
expect(results[0].name).toBe("makeStatement");
expect(results[0].isDefault).toBe(false);

In this case, the parseFunctionOrClass function returns an array of objects representing the exports. One entry for each export with information about their name, type and parameters.

The package exposes the following functions:

generateCodeFromAST
generateAstFromCode
isOfNodeType
getTypeSafeNode
parseFunctionOrClass

Can I help?

Yes, please. I've designed this lib very much for my current needs. If you want to help expand upon it, please put up a PR and I'll have a look at it as soon as I can.

How do I set it up?

// Install
npm i

// build
npm run build

// Test
npm t

How do I publish a new version?

(This is mainly because I myself sometimes forget) Bump the version in package.json and run the following command:

# Build the app in /dist
npm run build

# Publish it to npmjs.org
npm publish --access public

# Tag it
git tag -a vX.XX -m "What have you done!?"

# Push (preferably a branch and not main)
git push origin main

# Push it all
git push origin --tags