add

database/dev-tools.ts

+class DevAppTools {
+    private db!: IDBDatabase;
+
+    private readonly key = 'dev-tools';
+    private readonly valueKey = 'value';
+    private readonly table = 'dev-table';
+
+    private onReady() {
+        if (this.db) {
+            return Promise.resolve();
+        }
+        return new Promise<void>((resolve => {
+            if (indexedDB) {
+                const r = indexedDB.open(this.key, 1);
+                const setupDb = () => {
+                    if (this.db && !this.db.objectStoreNames.contains(this.table)) {
+                        this.db.createObjectStore(this.table, { keyPath: this.valueKey });
+                    }
+                    resolve();
+                };
+                r.onsuccess = (e) => {
+                    this.db = (e.target as any).result;
+                    setupDb();
+                };
+                r.onupgradeneeded = (e) => {
+                    this.db = (e.target as any).result;
+                    setupDb();
+                };
+                r.onerror = () => setupDb();
+            } else {
+                resolve();
+            }
+        }));
+    }
+
+    private buildTransaction(key: string) {
+        return this.db.transaction(key, "readwrite");
+    }
+
+    private buildStore(key: string) {
+        const transaction = this.buildTransaction(key);
+        return transaction.objectStore(key);
+    }
+
+    public isOpen() {
+        return new Promise<boolean>((resolve) => {
+            this.onReady().finally(() => {
+                if (!this.db) {
+                    return resolve(false);
+                }
+                const store = this.buildStore(this.table);
+                const r = store.getKey(1);
+                r.onsuccess = (o) => resolve((o.target as any).result);
+                r.onerror = () => resolve(false);
+            });
+        });
+    }
+
+    public toggle() {
+        return new Promise<boolean>((resolve) => {
+            this.onReady().finally(() => {
+                this.isOpen().then(r => {
+                    if (r) {
+                        const store = this.buildStore(this.table);
+                        const d = store.delete(1);
+                        d.onsuccess = () => resolve(false);
+                        d.onerror = () => resolve(false);
+                    } else {
+                        const store = this.buildStore(this.table);
+                        const d = store.add({ value: 1 });
+                        d.onsuccess = () => resolve(true);
+                        d.onerror = () => resolve(true);
+                    }
+                });
+            });
+        });
+    }
+}
+
+export const devAppTools = new DevAppTools();