index.js

$(document).ready(function() {
    $('#search').focus();
    $('#search').off('keyup');
    $('#search').on('keyup', function() {
        ajaxCall();
        $('iframe').attr('src', '');
    });
    $('.random').on('click', function() {
        randomFunction();
        $(this).text('Show me another random article!');
    });
});
function ajaxCall() {
    $.ajax({
        url: 'https://www.wikipedia.org/w/api.php?action=query&list=search&format=json&srsearch='+$('#search').val(),
        dataType: 'jsonp',
        type: 'GET',
        success: function(data) {
            $('#update').empty();
            var data = JSON.stringify(data);
            data = JSON.parse(data);

            var output = '';
            data.query.search.forEach(function(data) {
                var title = '<h2>'+data.title+'</h2><br>';
                var snippet = '<p>'+data.snippet+'</p>';
                var url = '<a href="https://en.wikipedia.org/wiki/'+data.title+'" target="_blank">';
                var endUrl = '</a>';
                output += url + title + endUrl + snippet + '<hr>';
            });
            $('#update').append(output);
        }
    });
}
function randomFunction() {
    $('#update').empty();
    $('#search').val('');
    $('iframe').attr('src', 'https://en.wikipedia.org/wiki/Special:Random');
}