1 files changed, 51 insertions, 0 deletions
diff --git a/src/doc/book/2018-edition/ferris.js b/src/doc/book/2018-edition/ferris.js
new file mode 100644
index 000000000..5e79b3c71
--- /dev/null
+++ b/src/doc/book/2018-edition/ferris.js
@@ -0,0 +1,51 @@
+var ferrisTypes = [
+  {
+    attr: 'does_not_compile',
+    title: 'This code does not compile!'
+  },
+  {
+    attr: 'panics',
+    title: 'This code panics!'
+  },
+  {
+    attr: 'unsafe',
+    title: 'This code block contains unsafe code.'
+  },
+  {
+    attr: 'not_desired_behavior',
+    title: 'This code does not produce the desired behavior.'
+  }
+]
+
+document.addEventListener('DOMContentLoaded', () => {
+  for (var ferrisType of ferrisTypes) {
+    attachFerrises(ferrisType)
+  }
+})
+
+function attachFerrises (type) {
+  var elements = document.getElementsByClassName(type.attr)
+
+  for (var codeBlock of elements) {
+    var lines = codeBlock.textContent.split(/\r|\r\n|\n/).length - 1;
+
+    if (lines >= 4) {
+      attachFerris(codeBlock, type)
+    }
+  }
+}
+
+function attachFerris (element, type) {
+  var a = document.createElement('a')
+  a.setAttribute('href', 'ch00-00-introduction.html#ferris')
+  a.setAttribute('target', '_blank')
+
+  var img = document.createElement('img')
+  img.setAttribute('src', 'img/ferris/' + type.attr + '.svg')
+  img.setAttribute('title', type.title)
+  img.className = 'ferris'
+
+  a.appendChild(img)
+
+  element.parentElement.insertBefore(a, element)
+}