1 files changed, 65 insertions, 0 deletions
diff --git a/src/doc/book/ferris.js b/src/doc/book/ferris.js
new file mode 100644
index 000000000..bb601a4e2
--- /dev/null
+++ b/src/doc/book/ferris.js
@@ -0,0 +1,65 @@
+var ferrisTypes = [
+  {
+    attr: 'does_not_compile',
+    title: 'This code does not compile!'
+  },
+  {
+    attr: 'panics',
+    title: 'This code panics!'
+  },
+  {
+    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.innerText.replace(/\n$/, '').split(/\n/).length
+    var size = 'large'
+    if (lines < 4) {
+      size = 'small'
+    }
+
+    var container = prepareFerrisContainer(codeBlock, size == 'small')
+    container.appendChild(createFerris(type, size))
+  }
+}
+
+function prepareFerrisContainer(element, useButtons) {
+  var foundButtons = element.parentElement.querySelector('.buttons')
+  if (useButtons && foundButtons) {
+    return foundButtons
+  }
+
+  var div = document.createElement('div')
+  div.classList.add('ferris-container')
+
+  element.parentElement.insertBefore(div, element)
+
+  return div
+}
+
+function createFerris(type, size) {
+  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.classList.add('ferris')
+  img.classList.add('ferris-' + size)
+
+  a.appendChild(img)
+
+  return a
+}