I have the following javascript code that convert date (string) to the Date Serial Number used in Microsoft Excel:

```function JSDateToExcelDate(inDate) {

var returnDateTime = 25569.0 + ((inDate.getTime() - (inDate.getTimezoneOffset() * 60 * 1000)) / (1000 * 60 * 60 * 24));
return returnDateTime.toString().substr(0,5);

}
```

So, how do I do the reverse? (Meaning that a Javascript code that convert the Date Serial Number used in Microsoft Excel to a date string?

Apr 11, 2022 in Database 3,120 views

## 1 answer to this question.

```function ExcelDateToJSDate(serial) {
var utc_days  = Math.floor(serial - 25569);
var utc_value = utc_days * 86400;
var date_info = new Date(utc_value * 1000);

var fractional_day = serial - Math.floor(serial) + 0.0000001;

var total_seconds = Math.floor(86400 * fractional_day);

var seconds = total_seconds % 60;

total_seconds -= seconds;

var hours = Math.floor(total_seconds / (60 * 60));
var minutes = Math.floor(total_seconds / 60) % 60;

return new Date(date_info.getFullYear(), date_info.getMonth(), date_info.getDate(), hours, minutes, seconds);
}```

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