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localforage.js
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localforage.js
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import idbDriver from './drivers/indexeddb';
import websqlDriver from './drivers/websql';
import localstorageDriver from './drivers/localstorage';
import serializer from './utils/serializer';
import Promise from './utils/promise';
import executeCallback from './utils/executeCallback';
import executeTwoCallbacks from './utils/executeTwoCallbacks';
import includes from './utils/includes';
import isArray from './utils/isArray';
// Drivers are stored here when `defineDriver()` is called.
// They are shared across all instances of localForage.
const DefinedDrivers = {};
const DriverSupport = {};
const DefaultDrivers = {
INDEXEDDB: idbDriver,
WEBSQL: websqlDriver,
LOCALSTORAGE: localstorageDriver
};
const DefaultDriverOrder = [
DefaultDrivers.INDEXEDDB._driver,
DefaultDrivers.WEBSQL._driver,
DefaultDrivers.LOCALSTORAGE._driver
];
const OptionalDriverMethods = ['dropInstance'];
const LibraryMethods = [
'clear',
'getItem',
'iterate',
'key',
'keys',
'length',
'removeItem',
'setItem'
].concat(OptionalDriverMethods);
const DefaultConfig = {
description: '',
driver: DefaultDriverOrder.slice(),
name: 'localforage',
// Default DB size is _JUST UNDER_ 5MB, as it's the highest size
// we can use without a prompt.
size: 4980736,
storeName: 'keyvaluepairs',
version: 1.0
};
function callWhenReady(localForageInstance, libraryMethod) {
localForageInstance[libraryMethod] = function() {
const _args = arguments;
return localForageInstance.ready().then(function() {
return localForageInstance[libraryMethod].apply(
localForageInstance,
_args
);
});
};
}
function extend() {
for (let i = 1; i < arguments.length; i++) {
const arg = arguments[i];
if (arg) {
for (let key in arg) {
if (arg.hasOwnProperty(key)) {
if (isArray(arg[key])) {
arguments[0][key] = arg[key].slice();
} else {
arguments[0][key] = arg[key];
}
}
}
}
}
return arguments[0];
}
class LocalForage {
constructor(options) {
for (let driverTypeKey in DefaultDrivers) {
if (DefaultDrivers.hasOwnProperty(driverTypeKey)) {
const driver = DefaultDrivers[driverTypeKey];
const driverName = driver._driver;
this[driverTypeKey] = driverName;
if (!DefinedDrivers[driverName]) {
// we don't need to wait for the promise,
// since the default drivers can be defined
// in a blocking manner
this.defineDriver(driver);
}
}
}
this._defaultConfig = extend({}, DefaultConfig);
this._config = extend({}, this._defaultConfig, options);
this._driverSet = null;
this._initDriver = null;
this._ready = false;
this._dbInfo = null;
this._wrapLibraryMethodsWithReady();
this.setDriver(this._config.driver).catch(() => {});
}
// Set any config values for localForage; can be called anytime before
// the first API call (e.g. `getItem`, `setItem`).
// We loop through options so we don't overwrite existing config
// values.
config(options) {
// If the options argument is an object, we use it to set values.
// Otherwise, we return either a specified config value or all
// config values.
if (typeof options === 'object') {
// If localforage is ready and fully initialized, we can't set
// any new configuration values. Instead, we return an error.
if (this._ready) {
return new Error(
"Can't call config() after localforage " + 'has been used.'
);
}
for (let i in options) {
if (i === 'storeName') {
options[i] = options[i].replace(/\W/g, '_');
}
if (i === 'version' && typeof options[i] !== 'number') {
return new Error('Database version must be a number.');
}
this._config[i] = options[i];
}
// after all config options are set and
// the driver option is used, try setting it
if ('driver' in options && options.driver) {
return this.setDriver(this._config.driver);
}
return true;
} else if (typeof options === 'string') {
return this._config[options];
} else {
return this._config;
}
}
// Used to define a custom driver, shared across all instances of
// localForage.
defineDriver(driverObject, callback, errorCallback) {
const promise = new Promise(function(resolve, reject) {
try {
const driverName = driverObject._driver;
const complianceError = new Error(
'Custom driver not compliant; see ' +
'https://mozilla.github.io/localForage/#definedriver'
);
// A driver name should be defined and not overlap with the
// library-defined, default drivers.
if (!driverObject._driver) {
reject(complianceError);
return;
}
const driverMethods = LibraryMethods.concat('_initStorage');
for (let i = 0, len = driverMethods.length; i < len; i++) {
const driverMethodName = driverMethods[i];
// when the property is there,
// it should be a method even when optional
const isRequired = !includes(
OptionalDriverMethods,
driverMethodName
);
if (
(isRequired || driverObject[driverMethodName]) &&
typeof driverObject[driverMethodName] !== 'function'
) {
reject(complianceError);
return;
}
}
const configureMissingMethods = function() {
const methodNotImplementedFactory = function(methodName) {
return function() {
const error = new Error(
`Method ${methodName} is not implemented by the current driver`
);
const promise = Promise.reject(error);
executeCallback(
promise,
arguments[arguments.length - 1]
);
return promise;
};
};
for (
let i = 0, len = OptionalDriverMethods.length;
i < len;
i++
) {
const optionalDriverMethod = OptionalDriverMethods[i];
if (!driverObject[optionalDriverMethod]) {
driverObject[
optionalDriverMethod
] = methodNotImplementedFactory(
optionalDriverMethod
);
}
}
};
configureMissingMethods();
const setDriverSupport = function(support) {
if (DefinedDrivers[driverName]) {
console.info(
`Redefining LocalForage driver: ${driverName}`
);
}
DefinedDrivers[driverName] = driverObject;
DriverSupport[driverName] = support;
// don't use a then, so that we can define
// drivers that have simple _support methods
// in a blocking manner
resolve();
};
if ('_support' in driverObject) {
if (
driverObject._support &&
typeof driverObject._support === 'function'
) {
driverObject._support().then(setDriverSupport, reject);
} else {
setDriverSupport(!!driverObject._support);
}
} else {
setDriverSupport(true);
}
} catch (e) {
reject(e);
}
});
executeTwoCallbacks(promise, callback, errorCallback);
return promise;
}
driver() {
return this._driver || null;
}
getDriver(driverName, callback, errorCallback) {
const getDriverPromise = DefinedDrivers[driverName]
? Promise.resolve(DefinedDrivers[driverName])
: Promise.reject(new Error('Driver not found.'));
executeTwoCallbacks(getDriverPromise, callback, errorCallback);
return getDriverPromise;
}
getSerializer(callback) {
const serializerPromise = Promise.resolve(serializer);
executeTwoCallbacks(serializerPromise, callback);
return serializerPromise;
}
ready(callback) {
const self = this;
const promise = self._driverSet.then(() => {
if (self._ready === null) {
self._ready = self._initDriver();
}
return self._ready;
});
executeTwoCallbacks(promise, callback, callback);
return promise;
}
setDriver(drivers, callback, errorCallback) {
const self = this;
if (!isArray(drivers)) {
drivers = [drivers];
}
const supportedDrivers = this._getSupportedDrivers(drivers);
function setDriverToConfig() {
self._config.driver = self.driver();
}
function extendSelfWithDriver(driver) {
self._extend(driver);
setDriverToConfig();
self._ready = self._initStorage(self._config);
return self._ready;
}
function initDriver(supportedDrivers) {
return function() {
let currentDriverIndex = 0;
function driverPromiseLoop() {
while (currentDriverIndex < supportedDrivers.length) {
let driverName = supportedDrivers[currentDriverIndex];
currentDriverIndex++;
self._dbInfo = null;
self._ready = null;
return self
.getDriver(driverName)
.then(extendSelfWithDriver)
.catch(driverPromiseLoop);
}
setDriverToConfig();
const error = new Error(
'No available storage method found.'
);
self._driverSet = Promise.reject(error);
return self._driverSet;
}
return driverPromiseLoop();
};
}
// There might be a driver initialization in progress
// so wait for it to finish in order to avoid a possible
// race condition to set _dbInfo
const oldDriverSetDone =
this._driverSet !== null
? this._driverSet.catch(() => Promise.resolve())
: Promise.resolve();
this._driverSet = oldDriverSetDone
.then(() => {
const driverName = supportedDrivers[0];
self._dbInfo = null;
self._ready = null;
return self.getDriver(driverName).then(driver => {
self._driver = driver._driver;
setDriverToConfig();
self._wrapLibraryMethodsWithReady();
self._initDriver = initDriver(supportedDrivers);
});
})
.catch(() => {
setDriverToConfig();
const error = new Error('No available storage method found.');
self._driverSet = Promise.reject(error);
return self._driverSet;
});
executeTwoCallbacks(this._driverSet, callback, errorCallback);
return this._driverSet;
}
supports(driverName) {
return !!DriverSupport[driverName];
}
_extend(libraryMethodsAndProperties) {
extend(this, libraryMethodsAndProperties);
}
_getSupportedDrivers(drivers) {
const supportedDrivers = [];
for (let i = 0, len = drivers.length; i < len; i++) {
const driverName = drivers[i];
if (this.supports(driverName)) {
supportedDrivers.push(driverName);
}
}
return supportedDrivers;
}
_wrapLibraryMethodsWithReady() {
// Add a stub for each driver API method that delays the call to the
// corresponding driver method until localForage is ready. These stubs
// will be replaced by the driver methods as soon as the driver is
// loaded, so there is no performance impact.
for (let i = 0, len = LibraryMethods.length; i < len; i++) {
callWhenReady(this, LibraryMethods[i]);
}
}
createInstance(options) {
return new LocalForage(options);
}
}
// The actual localForage object that we expose as a module or via a
// global. It's extended by pulling in one of our other libraries.
export default new LocalForage();