Improve how plugin javascript is loaded

- Load the plugins after Reveal.initialize or some plugins don't work
- Put the object.assign polyfill in its own file

layouts/partials/layout/javascript.html

@@ -1,3 +1,5 @@
+<!-- polyfill needed for IE11 and below -->
+<script type="text/javascript" src={{ "reveal-hugo/object-assign.js" | relURL }}></script>
 <!-- Printing and PDF exports -->
 <!-- use Hugo to create the right path for the print stylesheet, then conditionally include it -->
 {{- $reveal_location := $.Param "reveal_hugo.reveal_cdn" | default "reveal-js" -}}
@@ -17,48 +19,7 @@
 <script src="{{ printf "%s/lib/js/head.min.js" $reveal_location | relURL }}"></script>
 <script src="{{ printf "%s/js/reveal.js" $reveal_location | relURL }}"></script>
 <!-- load Reveal.js plugins -->
-<script type="text/javascript" src="{{ printf "%s/lib/js/classList.js" $reveal_location | relURL }}"></script>
-{{ $default_plugins := slice "plugin/markdown/marked.js" "plugin/markdown/markdown.js" "plugin/highlight/highlight.js" "plugin/zoom-js/zoom.js" }}
-{{ range $default_plugins }}
-<script type="text/javascript" src="{{ printf "%s/%s" $reveal_location . | relURL }}"></script>
-{{ end }}
-<!-- always use local version of the notes plugin since HTML file it requires isn't on CDN -->
-<script type="text/javascript" src="{{ "reveal-js/plugin/notes/notes.js" | relURL }}"></script>
-<!-- load custom plugins locally only (not CDN since many plugins won't exist there) -->
-{{ range $.Param "reveal_hugo.plugins" }}
-<script type="text/javascript" src="{{ . | relURL }}"></script>
-{{ end }}
 <script type="text/javascript">
-  // polyfill needed for IE11 and below
-  if (typeof Object.assign != 'function') {
-    // Must be writable: true, enumerable: false, configurable: true
-    Object.defineProperty(Object, "assign", {
-      value: function assign(target, varArgs) { // .length of function is 2
-        'use strict';
-        if (target == null) { // TypeError if undefined or null
-          throw new TypeError('Cannot convert undefined or null to object');
-        }
-
-        var to = Object(target);
-
-        for (var index = 1; index < arguments.length; index++) {
-          var nextSource = arguments[index];
-
-          if (nextSource != null) { // Skip over if undefined or null
-            for (var nextKey in nextSource) {
-              // Avoid bugs when hasOwnProperty is shadowed
-              if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {
-                to[nextKey] = nextSource[nextKey];
-              }
-            }
-          }
-        }
-        return to;
-      },
-      writable: true,
-      configurable: true
-    });
-  }
   // Hugo lowercases all params and Reveal.js needs camelcase
   // So params in Hugo must be stored in snakecase and we camelize them here
   function camelize(map) {
@@ -83,5 +44,21 @@
     camelize(revealHugoSiteParams),
     camelize(revealHugoPageParams));
   Reveal.initialize(options);
+</script>
+<!-- load Reveal.js plugins after Reveal.js is initialized -->
+<script type="text/javascript" src="{{ printf "%s/lib/js/classList.js" $reveal_location | relURL }}"></script>
+{{ $default_plugins := slice "plugin/markdown/marked.js" "plugin/markdown/markdown.js" "plugin/highlight/highlight.js" "plugin/zoom-js/zoom.js" }}
+{{ range $default_plugins }}
+<script type="text/javascript" src="{{ printf "%s/%s" $reveal_location . | relURL }}"></script>
+{{ end }}
+<!-- always use local version of the notes plugin since HTML file it requires isn't on CDN -->
+<script type="text/javascript" src="{{ "reveal-js/plugin/notes/notes.js" | relURL }}"></script>
+<!-- load custom plugins locally only (not CDN since many plugins won't exist there) -->
+{{ range $.Param "reveal_hugo.plugins" }}
+<script type="text/javascript" src="{{ . | relURL }}"></script>
+{{ end }}
+<!-- init highlighting plugin if it was loaded -->
+<script type="text/javascript">
+if (hljs)
   hljs.initHighlightingOnLoad();
 </script>

static/reveal-hugo/object-assign.js

@@ -0,0 +1,29 @@
+if (typeof Object.assign != 'function') {
+  // Must be writable: true, enumerable: false, configurable: true
+  Object.defineProperty(Object, "assign", {
+    value: function assign(target, varArgs) { // .length of function is 2
+      'use strict';
+      if (target == null) { // TypeError if undefined or null
+        throw new TypeError('Cannot convert undefined or null to object');
+      }
+
+      var to = Object(target);
+
+      for (var index = 1; index < arguments.length; index++) {
+        var nextSource = arguments[index];
+
+        if (nextSource != null) { // Skip over if undefined or null
+          for (var nextKey in nextSource) {
+            // Avoid bugs when hasOwnProperty is shadowed
+            if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {
+              to[nextKey] = nextSource[nextKey];
+            }
+          }
+        }
+      }
+      return to;
+    },
+    writable: true,
+    configurable: true
+  });
+}