Moves localstorage handlers into its own file

bookwyrm/static/js/localstorage.js

@@ -0,0 +1,27 @@
+// set javascript listeners
+window.onload = function() {
+    // display based on localstorage vars
+    document.querySelectorAll('[data-hide]')
+        .forEach(t => setDisplay(t));
+
+    // update localstorage
+    Array.from(document.getElementsByClassName('set-display'))
+        .forEach(t => t.onclick = updateDisplay);
+};
+
+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);
+
+    document.querySelectorAll('[data-hide="' + key + '"]')
+        .forEach(t => setDisplay(t));
+}
+
+function setDisplay(el) {
+    // used in set reading goal
+    var key = el.getAttribute('data-hide');
+    var value = window.localStorage.getItem(key);
+    addRemoveClass(el, 'hidden', value);
+}