ast-reducers-transform.js

// transform.js
const fs = require('fs');
const parser = require('@babel/parser').parse;
const traverse = require('@babel/traverse').default;
const generate = require('@babel/generator').default;
const t = require("@babel/types");
const prettier = require('prettier');

const fileLocation = './reducers.js';
const file = fs.readFileSync(fileLocation).toString();
const ast = parser(file, {sourceType: 'module'});

const REDUCER_NAME = 'mice';
let lastImport;
let properties;

// Traverse the AST to find the nodes we need.
traverse(ast, {
  ImportDeclaration(path) {
    lastImport = path;
  },

  ObjectExpression(path) {
    properties = path.parent.declaration.properties
  },
})

// add import to AST
const importCode = `import ${REDUCER_NAME} from './${REDUCER_NAME}'`;
lastImport.insertAfter(parser(importCode, {sourceType: 'module'}));

// add export to AST
const id = t.identifier(REDUCER_NAME)
properties.push(t.objectProperty(id, id, false, true))

const newCode = generate(ast).code;
const prettifiedCode = prettier.format(newCode, { parser: 'babylon' })

fs.writeFile('transformed.js', prettifiedCode, (err) => {
  if (err) throw new Error(`addToReducerIndex.js write error: ${err}`)
});