The HTML Code
Calculated values are displayed within read-only inputs. These are rendered borderless with a light gray background using CSS to differentiate these from input fields.
Before we get into the minutiae of the markup, let's take a look at the form without CSS or JS, just to see what types of calculations we'll eventually have to perform:
On what day of the week were you born?
Please Enter your birthday(then click the “Update”button)
To get a feel for the formatted output data, here are the results for top Canadian tennis pro Milos Raonic, who was born on December 27th, 1990: