const ul = document.querySelector('#names');
const wordElem = document.querySelector('#word');

var namesArray = [
    'Pete Elemér',
    'Vihar Elek',
    'Roham Gábor',
    'Piti Ilona',
    'Landos Viktor',
    'Anda Zsolt'
];

namesArray.forEach(name => {
    var li = document.createElement('li');
    li.textContent = name;
    ul.appendChild(li);
});

wordElem.addEventListener('keyup', () => {
    console.log(wordElem.value);
    let a = namesArray.filter( element => {
        if (element.indexOf(wordElem.value)>-1) return element;
    });
    ul.innerHTML = '';
    a.forEach( name => {
        var li = document.createElement('li');
        li.textContent = name;
        ul.appendChild(li);        
    })
});