[assets] Use classes for JS files:

- Classes strictly parse code implicitly.
- Fix previously updated code.

bookwyrm/static/js/localstorage.js

@@ -1,28 +1,32 @@
-/* exported updateDisplay */
-/* globals addRemoveClass */
+/* exported LocalStorageTools */
+/* globals BookWyrm */
 
-// set javascript listeners
-function updateDisplay(e) {
-    // used in set reading goal
-    var key = e.target.getAttribute('data-id');
-    var value = e.target.getAttribute('data-value');
-    window.localStorage.setItem(key, value);
+let LocalStorageTools = new class {
+    constructor() {
+        // display based on localstorage vars
+        document.querySelectorAll('[data-hide]')
+            .forEach(t => this.setDisplay(t));
 
-    document.querySelectorAll('[data-hide="' + key + '"]')
-        .forEach(t => setDisplay(t));
+        // update localstorage
+        document.querySelectorAll('.set-display')
+            .forEach(t => t.onclick = this.updateDisplay.bind(this));
+    }
+
+    // set javascript listeners
+    updateDisplay(e) {
+        // used in set reading goal
+        var key = e.target.getAttribute('data-id');
+        var value = e.target.getAttribute('data-value');
+        window.localStorage.setItem(key, value);
+
+        document.querySelectorAll('[data-hide="' + key + '"]')
+            .forEach(t => this.setDisplay(t));
+    }
+
+    setDisplay(el) {
+        // used in set reading goal
+        var key = el.getAttribute('data-hide');
+        var value = window.localStorage.getItem(key);
+        BookWyrm.addRemoveClass(el, 'hidden', value);
+    }
 }
-
-function setDisplay(el) {
-    // used in set reading goal
-    var key = el.getAttribute('data-hide');
-    var value = window.localStorage.getItem(key);
-    addRemoveClass(el, 'hidden', value);
-}
-
-// display based on localstorage vars
-document.querySelectorAll('[data-hide]')
-    .forEach(t => setDisplay(t));
-
-// update localstorage
-document.querySelectorAll('.set-display')
-    .forEach(t => t.onclick = updateDisplay);