Caption concatenation when clicking through multiple images

//Problem: User when clicking on image goes to a dead end
//Solution: Create an overlay with the large image - Lightbox

var $overlay = $('<div id="overlay"></div>');
var $image = $('<img>');
var $caption = $("<p></p>");

// An image to the overlay
$overlay.append($image);

// A caption to overlay
$overlay.append($caption);
// Add overlay
$("body").append($overlay);

// Capture the click event on a link to an image.
$("#imageGallery a").click(function(event){
  event.preventDefault();
  var href = $(this).attr("href");
  console.log(href);

  // Show the overlay.
  $overlay.show();

  // Update overlay with the image linked in the link
  $image.attr('src', href);

  // Get child's alt attribute and set caption
  var captionText = $(this).children("img").attr("alt");
  $caption.append(captionText);

});


// When overlay is clicked 
  // Hide the overlay
  $overlay.click(function(){
  $overlay.hide();
  });