diff --git a/.eslintrc.json b/.eslintrc.json
index 8735899960..2c50b93462 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -25,6 +25,7 @@
         "popovers": false,
         "server_events": false,
         "ui": false,
+        "lightbox": false,
         "stream_color": false,
         "people": false,
         "navigate": false,
diff --git a/static/js/click_handlers.js b/static/js/click_handlers.js
index d10a8af7ba..4eeb4566b4 100644
--- a/static/js/click_handlers.js
+++ b/static/js/click_handlers.js
@@ -523,12 +523,12 @@ $(function () {
             e.stopPropagation();
 
             if ($target.parent().hasClass("youtube-video")) {
-                ui.lightbox({
+                lightbox.open({
                     type: "youtube",
                     id: $target.data("id"),
                 });
             } else {
-                ui.lightbox({
+                lightbox.open({
                     type: "photo",
                     image: img,
                     user: user,
diff --git a/static/js/lightbox.js b/static/js/lightbox.js
new file mode 100644
index 0000000000..fac50811ba
--- /dev/null
+++ b/static/js/lightbox.js
@@ -0,0 +1,58 @@
+var lightbox = (function () {
+var exports = {};
+
+function display_image(image, user) {
+    // image should be an Image Object in JavaScript.
+    var url = $(image).attr("src");
+    var title = $(image).parent().attr("title");
+
+    $("#overlay .player-container").hide();
+    $("#overlay .image-actions, .image-description, .download").show();
+
+    var img = new Image();
+    img.src = url;
+    $("#overlay .image-preview").html("").show()
+        .append(img);
+
+    $(".image-description .title").text(title || "N/A");
+    $(".image-description .user").text(user);
+
+    $(".image-actions .open, .image-actions .download").attr("href", url);
+}
+
+function display_youtube_video(id) {
+    $("#overlay .image-preview, .image-description, .download").hide();
+
+    var iframe = document.createElement("iframe");
+    iframe.width = window.innerWidth;
+    iframe.height = window.innerWidth * 0.5625;
+    iframe.src = "https://www.youtube.com/embed/" + id;
+    iframe.setAttribute("frameborder", 0);
+    iframe.setAttribute("allowfullscreen", true);
+
+    $("#overlay .player-container").html("").show().append(iframe);
+    $(".image-actions .open").attr("href", "https://youtu.be/" + id);
+}
+
+exports.open = function (data) {
+    switch (data.type) {
+        case "photo":
+            display_image(data.image, data.user);
+            break;
+        case "youtube":
+            display_youtube_video(data.id);
+            break;
+        default:
+            break;
+    }
+
+    $("#overlay").addClass("show");
+    popovers.hide_all();
+};
+
+return exports;
+}());
+
+if (typeof module !== 'undefined') {
+    module.exports = lightbox;
+}
diff --git a/static/js/ui.js b/static/js/ui.js
index 4ec811ccdb..3a408035c0 100644
--- a/static/js/ui.js
+++ b/static/js/ui.js
@@ -262,22 +262,6 @@ exports.show_failed_message_success = function (message_id) {
     });
 };
 
-exports.lightbox = function (data) {
-    switch (data.type) {
-        case "photo":
-            exports.lightbox_photo(data.image, data.user);
-            break;
-        case "youtube":
-            exports.youtube_video(data.id);
-            break;
-        default:
-            break;
-    }
-
-    $("#overlay").addClass("show");
-    popovers.hide_all();
-};
-
 $(document).ready(function () {
     var info_overlay_toggle = components.toggle({
         name: "info-overlay-toggle",
@@ -311,40 +295,6 @@ exports.show_info_overlay = function (target) {
     }
 };
 
-exports.lightbox_photo = function (image, user) {
-    // image should be an Image Object in JavaScript.
-    var url = $(image).attr("src");
-    var title = $(image).parent().attr("title");
-
-    $("#overlay .player-container").hide();
-    $("#overlay .image-actions, .image-description, .download").show();
-
-    var img = new Image();
-    img.src = url;
-    $("#overlay .image-preview").html("").show()
-        .append(img);
-
-    $(".image-description .title").text(title || "N/A");
-    $(".image-description .user").text(user);
-
-    $(".image-actions .open, .image-actions .download").attr("href", url);
-};
-
-exports.youtube_video = function (id) {
-    $("#overlay .image-preview, .image-description, .download").hide();
-
-    var iframe = document.createElement("iframe");
-    iframe.width = window.innerWidth;
-    iframe.height = window.innerWidth * 0.5625;
-    iframe.src = "https://www.youtube.com/embed/" + id;
-    iframe.setAttribute("frameborder", 0);
-    iframe.setAttribute("allowfullscreen", true);
-
-    $("#overlay .player-container").html("").show().append(iframe);
-    $(".image-actions .open").attr("href", "https://youtu.be/" + id);
-};
-// k3O01EfM5fU
-
 var loading_more_messages_indicator_showing = false;
 exports.show_loading_more_messages_indicator = function () {
     if (! loading_more_messages_indicator_showing) {
diff --git a/zproject/settings.py b/zproject/settings.py
index 3e021ef71c..dc1a3f5e9b 100644
--- a/zproject/settings.py
+++ b/zproject/settings.py
@@ -848,6 +848,7 @@ JS_SPECS = {
             'js/condense.js',
             'js/resize.js',
             'js/floating_recipient_bar.js',
+            'js/lightbox.js',
             'js/ui.js',
             'js/pointer.js',
             'js/click_handlers.js',