04. Party Time Associative Arrays

function partyTime(input) {
    let guests = {
        'vip': [],
        'regular': []
    };
    let index = input.indexOf('PARTY');
    let invites = input.slice(0, index);
    let party = input.slice(index + 1);

    for (let guest of invites) {
        if (isNaN(guest[0]) === false) {
            guests['vip'].push(guest);
        } else {
            guests['regular'].push(guest);
        }
    }
    for (let guest of party) {
        if (guests['vip'].includes(guest)) {
            guests['vip'].splice(guests['vip'].indexOf(guest), 1);
        } else {
            guests['regular'].splice(guests['regular'].indexOf(guest), 1);
        }
    }
    let output = [];
    for (let i = 0; i < guests['vip'].length; i++) {
        output.push(guests['vip'][i]);
    }
    for (let i = 0; i < guests['regular'].length; i++) {
        output.push(guests['regular'][i]);
    }
    let length = output.length;
    console.log(length);
    console.log(output.join('\n'));
}