JavaScript Doesn’t have a built-in function to add a button but you can create it. In function Add days to a new instance of JavaScript Date.
Example add days to date in JavaScript
HTML example code where we create function. A function takes 2 inputs first for the date and the second is for the day.
This takes care of automatically incrementing the month if necessary.
<!DOCTYPE html> 
<html>  
<body> 
    <script> 
        function addDays(date, days) {
          var result = new Date(date);
          result.setDate(result.getDate() + days);
          return result;
      }
      console.log(addDays('2020-01-30',1));
  </script> 
</body> 
</html>Output:

Q: How to add days to the current date in JavaScript?
Answer: Same as above example, remove date parameter and use current date.
<!DOCTYPE html> 
<html>  
<body> 
    <script> 
        function addDays(days) {
          var result = new Date();
          result.setDate(result.getDate() + days);
          return result;
      }
      console.log(addDays(1));
  </script> 
</body> 
</html> Output:

Do comment if you have any doubts and suggestions on this topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version