batch-git-mv.js

const glob = require('glob');
const child_process = require('child_process');
const util = require('util');
const exec = util.promisify(child_process.exec);

glob('src/**/*.js', async (err, files) => {
    console.log(files);
    for (let file of files) {
        await exec(`git mv ${file} ${file.replace('.js', '.ts')}`);
    }
});