lettercount.js

const glob = require('glob');
const fs = require('fs');

const files = glob.sync(process.cwd() + '/{src,config,scripts}/**/*.{js,jsx,ts,tsx}', {nodir: true});
const letterCount = files
.map((file) => fs.readFileSync(file, { encoding: 'utf-8'}))
.map((fileContent) => fileContent.split(''))
.reduce((acc, lettersOfFile) => {
    lettersOfFile.forEach((letter) => {
        acc[letter] = acc[letter] ? acc[letter]+1 : 1;
    })
    return acc;
}, {});

const sorted = Object.entries(letterCount).sort((a, b) => b[1] < a[1] ? -1 : 1)
console.table(sorted);