GULP script: delete not matching compiled .js & .js.map

const gulp = require('gulp');
const path = require('path');
const del = require('del');
const recursiveReaddir = require('recursive-readdir');
const _ = require('lodash');

gulp.watch('src/**/*.ts', async function clean (done) {
  const srcFiles = await new Promise((resolve, reject) => {
    recursiveReaddir('src', (err, files) => {
      if(err) reject(err);
      const arr = files.map(file => path.basename(file))
        .filter(file => file.includes('.ts'))
        .map(file => path.basename(file, '.ts'));
      resolve(arr);
    });
  });
  let distFiles = await new Promise((resolve, reject) => {
    recursiveReaddir('dist', (err, files) => {
      if(err) reject(err);
      const arr = files.map(file => path.basename(file))
        .filter(file => file.includes('.js'))
        .map(file => path.basename(file, '.js'))
        .map(file => path.basename(file, '.js.map'))
      resolve(arr);
    });
  });
  distFiles = _.uniq(distFiles);
  const notFound = distFiles.filter(file => srcFiles.indexOf(file) === -1);
  notFound.forEach(file => {
    del([
      `dist/**/${file}.js`,
      `dist/**/${file}.js.map`
    ]);
  });
  done();
});