How to calculate the number of days between two js instances-javascript tips-js tutorial

This article mainly introduces the example code for calculating the number of days difference between two time periods in js. If you need it, please refer to it. The Code is as follows:

// Determine whether it is a leap year
Function isLeapYear (year ){
If (year % 4 = 0 & (year % 100! = 0) | (year % 400 = 0 )))
{
Return true;
}
Return false;
}
// Judge the two dates before and after
Function validatePeriod (fyear, fmonth, fday, byear, bmonth, bday ){
If (fyear <byear ){
Return true;
} Else if (fyear = byear ){
If (fmonth <bmonth ){
Return true;
} Else if (fmonth = bmonth ){
If (fday <= bday ){
Return true;
} Else {
Return false;
}
} Else {
Return false;
}
} Else {
Return false;
}
}
// Calculate the difference between the two dates
Function dateDiff (d1, d2 ){
Var disNum = compareDate (d1, d2 );
Return disNum;
}
Function compareDate (date1, date2)
{
Var regexp =/^ (\ d {1, 4}) [-| \.] {1} (\ d {1, 2}) [-| \.] {1} (\ d {1, 2}) $ /;
Var monthDays = [,];
Regexp. test (date1 );
Var date1Year = RegExp. $1;
Var date1Month = RegExp. $2;
Var date1Day = RegExp. $3;

Regexp. test (date2 );
Var date2Year = RegExp. $1;
Var date2Month = RegExp. $2;
Var date2Day = RegExp. $3;

If (validatePeriod (date1Year, date1Month, date1Day, date2Year, date2Month, date2Day )){
FirstDate = new Date (date1Year, date1Month, date1Day );
SecondDate = new Date (date2Year, date2Month, date2Day );

Result = Math. floor (secondDate. getTime ()-firstDate. getTime ()/(1000*3600*24 ));
For (j = date1Year; j <= date2Year; j ++ ){
If (isLeapYear (j )){
MonthDays [1] = 2;
} Else {
MonthDays [1] = 3;
}
For (I = date1Month-1; I Result = result-monthDays [I];
}
}
Return result;
} Else {
Alert ('Sorry, the first time must be earlier than the second time. Thank you! ');
Exit;
}
}

Call this function to pass two time values: 2013-01-19 2013-12-19

Days = dateDiff (d1, d2 );