refactor(build): modularize JS code

- replace gulp with rollup
- remove JS output from repo

_includes/mode-toggle.html

@@ -26,13 +26,12 @@
       let self = this;
 
       /* always follow the system prefers */
-      this.sysDarkPrefers.addEventListener("change", () => {
+      this.sysDarkPrefers.addEventListener('change', () => {
         if (self.hasMode) {
           if (self.isDarkMode) {
             if (!self.isSysDarkPrefer) {
               self.setDark();
             }
-
           } else {
             if (self.isSysDarkPrefer) {
               self.setLight();
@@ -43,9 +42,7 @@
         }
 
         self.notify();
-
       });
-
     } /* constructor() */
 
     get sysDarkPrefers() { return window.matchMedia("(prefers-color-scheme: dark)"); }
@@ -62,8 +59,7 @@
 
     /* get the current mode on screen */
     get modeStatus() {
-      if (this.isDarkMode
-        || (!this.hasMode && this.isSysDarkPrefer)) {
+      if (this.isDarkMode || (!this.hasMode && this.isSysDarkPrefer)) {
         return ModeToggle.DARK_MODE;
       } else {
         return ModeToggle.LIGHT_MODE;
@@ -93,37 +89,32 @@
       }, "*");
     }
 
+    flipMode() {
+      if (this.hasMode) {
+        if (this.isSysDarkPrefer) {
+          if (this.isLightMode) {
+            this.clearMode();
+          } else {
+            this.setLight();
+          }
+        } else {
+          if (this.isDarkMode) {
+            this.clearMode();
+          } else {
+            this.setDark();
+          }
+        }
+      } else {
+        if (this.isSysDarkPrefer) {
+          this.setLight();
+        } else {
+          this.setDark();
+        }
+      }
+
+      this.notify();
+    } /* flipMode() */
   } /* ModeToggle */
 
-  const toggle = new ModeToggle();
-
-  function flipMode() {
-    if (toggle.hasMode) {
-      if (toggle.isSysDarkPrefer) {
-        if (toggle.isLightMode) {
-          toggle.clearMode();
-        } else {
-          toggle.setLight();
-        }
-
-      } else {
-        if (toggle.isDarkMode) {
-          toggle.clearMode();
-        } else {
-          toggle.setDark();
-        }
-      }
-
-    } else {
-      if (toggle.isSysDarkPrefer) {
-        toggle.setLight();
-      } else {
-        toggle.setDark();
-      }
-    }
-
-    toggle.notify();
-
-  } /* flipMode() */
-
+  const modeToggle = new ModeToggle();
 </script>