function getValues() {
                let userString = document.getElementById("userString").value;
              
                let revString = reverseString(userString);
                displayString(revString);
              }
              
              function reverseString(input) {
                let revString = "";
              
                for (let i = input.length - 1; i >= 0; i--) {
                  let letter = input[i];
              
                  revString = revString + letter;
                }
              
                return revString;
              }
              
              function displayString(output) {
                document.getElementById("results").textContent = output;
                let alertBox = document.getElementById("alert");
              
                alertBox.classList.remove("invisible");
              }
              
            
          

Code Explanation

This program allows users to input a string and see its reverse version on the webpage. It is made up of three functions: `getValues`, `reverseString`, and `displayString`. When the user clicks a button on the page, `getValues` is triggered and retrieves the value of an input element with the ID "userString". It then calls `reverseString` with `userString` as an argument and stores the output in a variable named `revString`. Finally, it calls `displayString` with `revString` as an argument.

`reverseString` is a function that takes a string as input and returns the reversed version of the string. It initializes an empty string called `revString` and uses a for loop to iterate through the input string in reverse order. For each iteration, it retrieves the character at the current index and appends it to `revString`. Once the loop is finished, it returns `revString`. `displayString` is a function that accepts a string as input and displays it on the webpage. It sets the text content of an element with the ID "results" to the input string and makes visible an element with the ID "alert" by removing the class "invisible". In summary, this code provides a straightforward example of how to manipulate strings and display results on a webpage using JavaScript.