Duration of Date Calculator

Features and Functionality:

1. Tabs for Count Days and Add Days:

   • Count Days Tab: Allows you to input a start date and an end date, and it calculates the number of days between them.
   • Add Days Tab: Allows you to input a start date and the number of days to add to it, and it calculates the new date.

2. Result Display:

   • Displays the calculated result (either the number of days or the new date) in a prominent box below the buttons.

3. “Include End Date” Checkbox:

   • In the “Count Days” tab, you can choose whether to include the end date in the calculation by checking the checkbox.

How to Use:

1. Count Days:

   • Enter the start date and end date in the provided fields.
   • If you want to include the end date, check the “Include end date” checkbox.
   • Click “Calculate” to get the number of days between the two dates.

2. Add Days:

   • Enter the start date and the number of days to add.
   • Click “Calculate” to get the new date after adding the specified number of days.

How to Test:

1. Copy the code into an .html file.
2. Open the file in your browser.
3. Try using both tabs to calculate days between dates or add days to a start date.

This should give you a working Date Duration Calculator similar to the screenshot you shared. Let me know if you have any issues!