JS-按周分组的月份日期

我正在尝试记录。写下周数，然后写下该周的天数。例如，如果你输入2016年4月作为你想要的月份，它会显示weekNum
，那么在第1周，第1周是星期五，第2周是星期六。然后第2周3日是星期天，4日是星期一，以此类推。

//variables
var reqMon;
var todaysDate = new Date();
var currYr = todaysDate.getFullYear();
var currMon = todaysDate.getMonth();
var currDate = todaysDate.getDate();
var currDay = todaysDate.getDay();
//creates a month array.
var monthArray = new Array("January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December");
//creates a day array.
var weekDaysArray = new Array("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday");
//creates an array for how many days in each month. 
var maxMonthlyDays = new Array("31", "28", "31", "30", "31", "30", "31", "31", "30", "31", "30", "31");
//prompts user for numeric month.
var reqMon = parseInt(prompt("Enter desired month (Jan = 1, Dec = 12)"));
//validates users month input.
while (reqMon == "" || reqMon < 1 || reqMon > 12) { 
    reqMon = prompt("Invalid Entry. Please enter the month number again.")
}
//Step 3B. 
document.write(reqMon + "/" + currDate + "/" + currYr + "<br /><br />");
//Step 4.
document.write(monthArray[reqMon -1] + " " + currYr + "<br /><br />");
var dateComb = (reqMon + "/1/" + currYr);
var userIdate = new Date(dateComb);
var userDay = new Date(dateComb).getDay();
var userDate = new Date(dateComb).getDate();
var maxDays = maxMonthlyDays[reqMon -1];
var numberWeeks = maxMonthlyDays[reqMon - 1] / 6;
// ****************  STEP 5 **************.
//loops through weeks of month.
for (x = 1; x <= maxMonthlyDays[reqMon] / 6; x++) {
    document.write("<b>Week " + x + "<br /></b>");
    while (userDay <= 6 && userDate <= maxMonthlyDays[reqMon]) { 
        document.write(weekDaysArray[userDay] + " " + userDate + "<br />");
        userDay++;
        userDate++;
    }
}

我可以得到迭代并输出到屏幕上的weekNum，我可以得到所需月份的总天数来迭代并输出。但我似乎无法得到"只有第1、2、3天等在适当的周数下输出"。

提前谢谢。