feat(storage): clear() removes all entries in the storage engine

ionic/platform/storage/local-storage.ts

@@ -79,4 +79,15 @@ export class LocalStorage extends StorageEngine {
       }
     });
   }
+
+  clear(): Promise<any> {
+    return new Promise((resolve, reject) => {
+      try {
+        window.localStorage.clear();
+        resolve();
+      } catch (e) {
+        reject(e);
+      }
+    });
+  }
 }

ionic/platform/storage/sql.ts

@@ -142,6 +142,9 @@ export class SqlStorage extends StorageEngine {
   */
   remove(key: string): Promise<any> {
     return this.query('delete from kv where key = ?', [key]);
+  }
 
+  clear(): Promise<any> {
+    return this.query('delete from kv');
   }
 }

ionic/platform/storage/storage.ts

@@ -51,6 +51,10 @@ export class Storage {
   query(query: string, params?: any) {
     return this._strategy.query(query, params);
   }
+
+  clear() {
+    return this._strategy.clear();
+  }
 }
 
 export interface IStorageEngine {
@@ -75,4 +79,7 @@ export class StorageEngine {
   query(query: string, params?: any): Promise<any> {
     throw Error("query() not implemented for this storage engine");
   }
+  clear(): Promise<any> {
+    throw Error("clear() not implemented for this storage engine");
+  }
 }