SOURCE

function FORM(){
    return {
        "data":{
            "begin":"2022-01-01",
            "end":"2022-01-31"
        }
    }
}

function overMonth() {
    var starDate = FORM().data.begin;
    var endDate = FORM().data.end;
    if (starDate && endDate) {
        var sDate = new Date(starDate).getTime();
        var eDate = new Date(endDate).getTime();
        var date = new Date(starDate);
        date.setMonth(date.getMonth() + 1);
        date.setDate(0);
        var days = date.getDate();
        var thisMothDays = 1000 * 3600 * 24 * days
        if (eDate - sDate >= thisMothDays) {
            return false
        } else {
            return true
        }
    }
    else {
        return true
    }
}

result = overMonth()

console.log(result)