'add another image' button functionality

index.pug

@@ -31,7 +31,7 @@ html(lang="en-gb")
                 textarea#output
                 br
                 button#download download
-                button.pagination.prev add another image
+                button.pagination.prev#add add another image
                 button.pagination.start#reset start again
         script(type="module")
             include script.js

script.js

@@ -3,6 +3,8 @@ import init, {load_default_game_data, add_tiles} from './pkg/bitsy_tiles.js';
 async function run() {
     await init();
 
+    const output = document.getElementById("output");
+
     // hide all pages except start page
     for (let page of document.getElementsByClassName('page')) {
         page.style.display = "none";
@@ -103,6 +105,16 @@ async function run() {
     importButton.addEventListener("click",    addTiles);
     importButton.addEventListener("touchend", addTiles);
 
+    function addImage() {
+        gameDataInput.value = output.value;
+        output.value = "";
+    }
+
+    const addImageButton = document.getElementById("add");
+
+    addImageButton.addEventListener("click",    addImage);
+    addImageButton.addEventListener("touchend", addImage);
+
     function reset() {
         gameDataInput.innerHTML = '';
         preview.removeAttribute("src");