index.js

const {MongoClient} = require('mongodb');
const rewriteWithAwait = require('./rewrite-with-await.js');
const startShell = require('./start-shell.js');

function makeCollectionObject(nativeCollection) {
  return {
    insertOne: (...args) => {
      return nativeCollection.insertOne(...args);
    },
    findOne: (...args) => {
      return nativeCollection.findOne(...args);
    },
    find: (...args) => {
      return nativeCollection.find(...args).toArray();
    },
  };
}

function makeDbObject(nativeDb) {
  return new Proxy(
      {},
      {
        get(target, propKey) {
          return makeCollectionObject(nativeDb.collection(propKey));
        },
      },
  );
}

async function main() {
  const client = await MongoClient.connect('mongodb://localhost:27017/test', {
    useUnifiedTopology: true,
  });

  startShell({
    eval: async (replEval, cmd, context, filename) => {
      return await replEval(rewriteWithAwait(cmd), context, filename);
    },
    context: {
      db: makeDbObject(client.db()),
    },
  });
}

main();

rewrite-with-await.js

const {parse} = require('@babel/parser');
const generate = require('@babel/generator').default;
const traverse = require('@babel/traverse').default;
const {awaitExpression, isAwaitExpression} = require('@babel/types');

function rewriteWithAwait(cmd) {
  const ast = parse(cmd, {allowAwaitOutsideFunction: true});

  traverse(ast, {
    CallExpression: function(path) {
      if (isAwaitExpression(path.parent)) {
        return;
      }

      path.replaceWith(awaitExpression(path.node));
    },
  });

  return generate(ast).code;
}

module.exports = rewriteWithAwait;

start-shell.js

const nodeRepl = require('repl');
const {promisify} = require('util');

function startShell(options = {}) {
  const replInstance = nodeRepl.start({
    prompt: options.prompt,
  });

  Object.assign(
      replInstance.context,
      options.context,
  );

  const replEval = promisify(replInstance.eval.bind(replInstance));

  replInstance.eval = async (cmd, context, filename, callback) => {
    options.eval(replEval, cmd, context, filename)
        .then((res) => callback(null, res))
        .catch(callback);
  };

  return replInstance;
}

module.exports = startShell;