Javascript date processing time zone issue_time and date

Copy code The code is as follows:

//dateObj is a date object, days represents how much to add to this date Days, for example 4, 5 (days)
function dateAdd(dateObj,days){
var tempDate = dateObj.valueOf();
tempDate = tempDate days * 24 * 60 * 60 * 1000;
tempDate = new Date(tempDate);
return tempDate;
}

//Then use, create a date object
var dateValue = document.getElementById("XXYY"). value.split("-");
var custArvDateTwoValue = new Date(dateValue[0],dateValue[1]-1,dateValue[2]);
//Call dateAdd and add two days
custArvDateTwoValue = dateAdd(custArvDateTwoValue,2);
var year = custArvDateTwoValue.getFullYear();
var month = custArvDateTwoValue.getMonth() 1;
var days = custArvDateTwoValue.getDate();
month = month <= 9 ? "0" month : month;
days = days <= 9 ? "0" days : days;
document.getElementById("XX").value = year "-" month "-" days;

I found during testing that when the value of document.getElementById("XXYY").value is 2009-10-31
the returned value is actually 2009- 11-01

Other situations are correct, for example, if you enter 2009-10-01, it will return 2009-10-03
I also tried today and the last day of each month next year, only 2009 -10-31 has a problem (I tried many times, only this time has a problem, the difficulty is 32 days in this month)

When I try 2009-10-31, the returned is 2009-11-01 too Correct

In the end, it was found that it was a time zone problem, so if you find this kind of problem in the future, you can check to see if the time zone does not correspond.