02.Weekend or Working Day

function weekendOrWorkingDay(day) {

    if (day == "Monday" || day == "Tuesday" || day == "Wednesday" || day == "Thursday" || day == "Friday") {
        console.log("Working day");
    } else if (day == "Saturday" || day == "Sunday") {
        console.log("Weekend");
    } else {
        console.log("Error");
    }
}

Второ решение(switch):

function weekendOrWorkingDay(input) {
    let day = input[0];

    switch (day) {
        case "Monday":
        case "Tuesday":
        case "Wednesday":
        case "Thursday":
        case "Friday":
            console.log("Working day");
            break;
        case "Saturday":
        case "Sunday":
            console.log("Weekend");
            break;
        default:
            console.log("Error");
            break;
    }
}