pipeline.js

const splitCharacters = (str) => str.split('');
const splitWords = (str) => str.split(' ');
const combineAllCharacters = (str) => str.join('');
const filter = (fn) => (array) => array.filter(fn);
const map = (fn) => (array) => array.map(fn);
const append = (text) => (value) => value + text;
const removeTheLetter = (letter) => (sentence) => 
    sentence
    |> splitCharacters
    |> filter(c => c !== letter)
    |> combineAllCharacters;

const makeLetterUpperCase = (letter) => (sentence) => 
    sentence
    |> splitCharacters
    |> map(c => c === letter ? c.toUpperCase() : c)
    |> combineAllCharacters;

const removeWordsWithLessThanFourLetters = (sentence) =>
    sentence
    |> splitWords
    |> filter(word => word.length > 4 )
    |> combineAllCharacters;