script.js

    //Declaring and initializing variables
    let submit = document.getElementById("submit");
    let output = document.getElementById("output");

    submit.addEventListener("click", () => {
      //Create a Date object from input value
      let date1 = new Date(document.getElementById("date-1").value);
      let date2 = new Date(document.getElementById("date-2").value);

      //Check if the input dates are valid
      //If valid calculate the difference
      if (date1.getTime() && date2.getTime()) {
        //Calculate difference in time using getTime function
        //getTime calculates number of years since January 1,1970
        let timeDifference = date2.getTime() - date1.getTime();

        //Since this value is in milliseconds we need to convert it into days
        //We want the difference to be a non-negative number. Hence we use Math.abs()
        let dayDifference = (Math.abs(timeDifference / (1000 * 3600 * 24))) - 1;
        output.innerHTML = `<span>${dayDifference}</span> days between both the dates`;
      }

      //Else display that the input is valid
      else {
        output.innerHTML = "Please select a valid date";
      }
    });