diff --git a/src/theme/book.js b/src/theme/book.js
index a48ebcd2..e303ebb4 100644
--- a/src/theme/book.js
+++ b/src/theme/book.js
@@ -4,12 +4,14 @@
 window.onunload = function () { };
 
 // Global variable, shared between modules
-function playground_text(playground) {
+function playground_text(playground, hidden = true) {
     let code_block = playground.querySelector("code");
 
     if (window.ace && code_block.classList.contains("editable")) {
         let editor = window.ace.edit(code_block);
         return editor.getValue();
+    } else if (hidden) {
+        return code_block.textContent;
     } else {
         return code_block.innerText;
     }
@@ -599,7 +601,7 @@ function playground_text(playground) {
         text: function (trigger) {
             hideTooltip(trigger);
             let playground = trigger.closest("pre");
-            return playground_text(playground);
+            return playground_text(playground, false);
         }
     });