function splitString(str) {

    return String( str )

        .toLowerCase()

        .split( /\s|\b/ )

        .filter( function alpha(v){

            return /^[\w]+$/.test( v );

        } );

}

​

function deDuplicate(list) {

    return Array.from(new Set(list));

}

​

function skipShortWords(words) {    

    return words.filter(word => word.length > 4)

}

​

var compose = (...fns) =>

    result => {

        var list = fns.slice()

        while (list.length > 0) {

            result = list.pop()(result)

        }

        return result

    }

var data = "JavaScript is a programming language. JavaScript is easy to learn. Good Morning, JavaScript"

​

​

var result1 = skipShortWords( deDuplicate( splitString(data) ) )

​

var longWords = compose(skipShortWords, deDuplicate, splitString)

​

var result2 = longWords(data)

​

console.log(result1, result2)