Retrieve List Item Details

 function retrieveListItemDetails(listName, itemId) {

  // Get the current SharePoint context

  var context = SP.ClientContext.get_current();

  // Get the list

  var list = context.get_web().get_lists().getByTitle(listName);

  // Get the list item

  var listItem = list.getItemById(itemId);

  // Load the list item properties

  context.load(listItem);

  // Execute the query

  context.executeQueryAsync(

    function () {

      // On success, retrieve the item values

      var title = listItem.get_item('Title');

      var description = listItem.get_item('Description');

      // Concatenate the values into a query string parameter

      var queryStringParam = 'title=' + encodeURIComponent(title) +

        '&description=' + encodeURIComponent(description);

      // Pass the query string parameter to another application or redirect

      // Example: window.location.href = 'https://example.com/otherapp?' + queryStringParam;

      // Log the query string parameter for demonstration purposes

      console.log('Query string parameter:', queryStringParam);

    },

    function (sender, args) {

      // On error, log the error message

      console.log('Error:', args.get_message());

    }

  );

}