updoot

tgui/packages/common/storage.js

@@ -0,0 +1,76 @@
+/**
+ * Browser-agnostic abstraction of key-value web storage.
+ *
+ * @file
+ * @copyright 2020 Aleksej Komarov
+ * @license MIT
+ */
+
+export const STORAGE_NONE = 0;
+export const STORAGE_LOCAL_STORAGE = 1;
+export const STORAGE_INDEXED_DB = 2;
+
+const createMock = () => {
+  let storage = {};
+  const get = key => storage[key];
+  const set = (key, value) => {
+    storage[key] = value;
+  };
+  const remove = key => {
+    storage[key] = undefined;
+  };
+  const clear = () => {
+    // NOTE: On IE8, this will probably leak memory if used often.
+    storage = {};
+  };
+  return {
+    get,
+    set,
+    remove,
+    clear,
+    engine: STORAGE_NONE,
+  };
+};
+
+const createLocalStorage = () => {
+  const get = key => {
+    const value = localStorage.getItem(key);
+    if (typeof value !== 'string') {
+      return;
+    }
+    return JSON.parse(value);
+  };
+  const set = (key, value) => {
+    localStorage.setItem(key, JSON.stringify(value));
+  };
+  const remove = key => {
+    localStorage.removeItem(key);
+  };
+  const clear = () => {
+    localStorage.clear();
+  };
+  return {
+    get,
+    set,
+    remove,
+    clear,
+    engine: STORAGE_LOCAL_STORAGE,
+  };
+};
+
+const testLocalStorage = () => {
+  // Localstorage can sometimes throw an error, even if DOM storage is not
+  // disabled in IE11 settings.
+  // See: https://superuser.com/questions/1080011
+  try {
+    return Boolean(window.localStorage && window.localStorage.getItem);
+  }
+  catch {
+    return false;
+  }
+};
+
+export const storage = (
+  testLocalStorage() && createLocalStorage()
+  || createMock()
+);