arrayOfStringsCompare.js

const o = ['abc', 'hejhej', 'defg'];
const n = ['hejhej', 'defg', 'JOHAN'];

const getDiff = (current, neu) => {
    return neu.filter((item, index) => {
        if(current.indexOf(item) === -1) {
            return item 
        }
    })
}

console.log(getDiff(o, n)) // returns ['JOHAN']