gaf-mobile/support/service-worker/idb-helper.js

GAF mobile Web site

/**
 * A naive [and incomplete] implementation of IDBObjectStore methods wrapped in
 * Promises. This is to simplify interaction with IndexedDB, such as setting and
 * getting entries, to keep us sane. The set of methods implemented here is a
 * subset of the corresponding methods in IDBObjectStore.
 */

 /* global self */
'use strict';

(function() {
  function IDBHelper(dbName, version, callback) {
    var _db;

    var _getIdb = function() {
      if (_db) {
        return Promise.resolve(_db);
      }

      return new Promise(function(resolve, reject) {
        if (!self.indexedDB) { // IndexedDB is not supported
          return reject('IndexedDB is not supported on your browser.');
        }

        var request = self.indexedDB.open(dbName, version);
        request.onupgradeneeded = function(event) {
          var db = event.target.result;
          callback(db);
        };
        request.onsuccess = function(event) {
          _db = event.target.result;
          return resolve(_db);
        };
        request.onerror = function() {
          return reject('Cannot get IndexedDB named: ' + dbName);
        };
      });
    };

    return {
      transaction: function(store, mode, callback) {
        return _getIdb().then(function(db) {
          mode = mode || 'readonly';

          var txn = db.transaction(store, mode);
          var request = callback(txn);

          return new Promise(function(resolve, reject) {
            request.onsuccess = function() {
              resolve(request.result);
            };
            request.onerror = function() {
              reject(request.error);
            };
          });
        });
      },

      get: function(store, key) {
        return this.transaction(store, 'readonly', function(txn) {
          return txn.objectStore(store).get(key);
        });
      },

      put: function(store, key, value) {
        return this.transaction(store, 'readwrite', function(txn) {
          return txn.objectStore(store).put(value, key);
        });
      },

      delete: function(store, key) {
        return this.transaction(store, 'readwrite', function(txn) {
          return txn.objectStore(store).delete(key);
        });
      },

      getAllKeys: function(store) {
        return this.transaction(store, 'readonly', function(txn) {
          return txn.objectStore(store).getAllKeys();
        });
      }
    };
  }

  self.IDBHelper = IDBHelper;
}());