Word counter

words.js

'use strict';

const {readFile} = require('fs');

const uniq = (res, x) => {
    if (!~res.indexOf(x)){
        res.push(x);
    };

    return res;
};


function excludes(word){
    /* Должен вернуть false для всех слов исключений */
    return true
}

readFile('data.txt', 'utf-8', (err, data) => {
    const words = data
        .replace(/\n/g, ' ')
        .split(' ')
        .map(e => e.trim().toLowerCase())
        .filter(e => /^[a-zа-я]+$/.test(e))
        .filter(e => excludes(e))
        .filter(e => e.length > 3)

    const map = words.reduce((map, word) => {
        if (map[word]){
            map[word] += 1;
        } else {
            map[word] = 1
        }

        return map;
    }, {});

    const popular = Object.keys(map).map(word => ({[word]: map[word]})).sort((w1, w2) => {
        return w2[Object.keys(w2).pop()] - w1[Object.keys(w1).pop()]
    }).slice(0, 100);

});