javascript - 验证一个月的最后一个日期

Question

我有两个函数来计算用户输入的一个月的最后日期

var effectiveAsOfDateYear = document.forms[0].effectiveAsOfDateYear.value;   
var effectiveAsOfDateMonth = document.forms[0].effectiveAsOfDateMonth.value;          
var effectiveAsOfDateDay = document.forms[0].effectiveAsOfDateDay.value;                

userEnteredDate = effectiveAsOfDateDay; 

userEnteredMonth = effectiveAsOfDateMonth;

// **Then using if condition** 
if (!isLastDayOfMonth(userEnteredDate, userEnteredMonth))   {
alert("Inside isLastDayOfMonth of continueUploadReportAction ");
// Do something         
}
------------------------------------------------------------------
// The function is defined as below **strong text**          
function isLastDayOfMonth( date, month ) {
alert("Inside isLastDayOfMonth, the date is " + date );
alert("Inside isLastDayOfMonth, the month is " + month );
return ( date.toString() == new Date( date.getFullYear(), month, 0, 0, 0, 0, 0 ).toString() );
}

但是在运行时，当我选择月份为 7、日期为 24 时，传递给 isLastDayOfMonth 函数的实际值是alert("isLastDayOfMonth 内，日期为 "+ date ); 为 6和 alert("在 isLastDayOfMonth 内，月份是 "+ Month ); 是 24并且 return 似乎永远都不正确。

请提出更好的方法..

Answer 1

如果您有一个 JavaScript“Date”对象，您可以检查它是否是一个月的最后一天，如下所示:

function isLastDayOfMonth(d) {
  // create a new date that is the next day at the same time
  var nd = new Date(d.getTime());
  nd.setDate(d.getDate() + 1);

  // Check if the new date is in the same month as the passed in date. If the passed in date
  // is the last day of the month, the new date will be "pushed" into the next month.
  return nd.getMonth() === d.getMonth();
}