IndexedDB Polyfill


|Live Demo (stable)! | Live Demo (master)! |
| -------------- | ----------------- |

__Use a single, indexable, offline storage API across all desktop and mobile
browsers and Node.js.__

Even if a browser natively supports IndexedDB,
you may still want to use this shim. Some native IndexedDB implementations are
very buggy.
Others are missing certain features.
There are also many minor inconsistencies between different browser
implementations of IndexedDB, such as how errors are handled, how transaction
timing works, how records are sorted, how cursors behave, etc. Using this
shim will ensure consistent behavior across all browsers.

Features

- Optionally adds full IndexedDB support to any web browser that
supports WebSQL
- Does nothing if the browser already
natively supports IndexedDB
- Can _optionally replace_ native IndexedDB on browsers with
buggy implementations
- Works on __desktop__ and __mobile__ devices as well as __Node.js__ (courtesy of
websql which sits on top of SQLite3)
- Works on __Cordova__ and __PhoneGap__ via the
IndexedDB plug-in
(Not recently tested)
- This shim is basically an IndexedDB-to-WebSQL adapter.
- More (though most likely now outdated) details about the project at
gh-pages

Installation

You can download the development
or
production (minified)
script, or install it using NPM.

Please note that the version currently in master is the only one which
supports Node.js (and has a number of fixes), but we are not yet ready
for release.

For Mac, you may need to have CMake installed
for the SQLite3 install to work (See
Tools->How to Install For Command Line Use) as well as build SQLite3 from
source via npm install --build-from-source in the node-sqlite3 directory.
Also make sure Python (2.7) is installed.

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``shell
npm install indexeddbshim
`

or

`shell
yarn add indexeddbshim
`

Browser set-up

Add the following scripts to your page:

`html



`

If you need full Unicode compliance (handling special
non-alphanumeric identifiers in store and index names),
use the following instead:

`html



`

Node set-up

`js
const setGlobalVars = require('indexeddbshim');

global.window = global; // We'll allow ourselves to use window.indexedDB or indexedDB as a global
setGlobalVars(); // See signature below
`

ES6 Modules

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`js
import setGlobalVars from 'indexeddbshim';
`

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`js
import setGlobalVars from 'indexeddbshim/src/node-UnicodeIdentifiers';

// Or without Unicode support
// import setGlobalVars from 'indexeddbshim/src/node';
`

Usage/API

For the browser scripts, if the browser already natively supports IndexedDB
and is not known to be buggy, then the script won't do anything.

Otherwise, assuming WebSQL is available, the script will add the
IndexedDB API
to the browser (unless you use one of the non-invasive files, in which case
setGlobalVars can be used to optionally add the API to an object of your
choosing; if you also wish Unicode support, you will need to add it yourself).

Either way, you can use IndexedDB just like normal.
Here's an example.

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In the non-invasive builds (and Node.js), globals are not automatically set.
You have the choice to set globals when you wish as well as to set the API
on an object of your choosing in place of setting globals.

This is done through setGlobalVars() (which is otherwise called in the
browser builds automatically with no arguments).

This function defines shimIndexedDB, indexedDB, IDBFactory, etc. on
one of the following objects in order of precedence:

1. The passed in winObj object if defined
1. window (for Node, define global.window = global;)
1. self (for web workers)
1. global (for Node)
1. A new empty object

The initialConfig argument, if present, should be an object whose keys
are the config properties to set and its values are the config values (see
shimIndexedDB.__setConfig below).

If you are adding your own window.openDatabase implementation, supplying
it within initialConfig (keyed as openDatabase) will ensure that
shimIndexedDB.__useShim() is auto-invoked for you if poor IndexedDB
support is detected.

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To force IndexedDBShim to shim the browser's native IndexedDB (if our code
is not already auto-shimming your browser when detecting poor browser
support), add this method call to your script.

On browsers that support WebSQL, this line will _completely replace_ the
native IndexedDB implementation with the IndexedDBShim-to-WebSQL
implementation.

On browsers that _don't_ support WebSQL, but _do_ support IndexedDB, this
line will patch many known problems and add missing features. For example,
on Internet Explorer, this will add support for compound keys.

If CFG.addNonIDBGlobals has been set (e.g., on the initialConfig argument
of setGlobalVars), the other non-IndexedDB shims necessitated by this
library will be polyfilled as possible on the chosen "global" (i.e.,
ShimEvent, ShimCustomEvent, ShimEventTarget, ShimDOMException,
and ShimDOMStringList). Mostly useful for testing.

If CFG.replaceNonIDBGlobals is used, it will instead attempt to add,
or if already present, overwrite these globals.

If CFG.fullIDLSupport has been set, the slow-performing
Object.setPrototypeOf calls required for full WebIDL compliance will
be used. Probably only needed for testing or environments where full
introspection on class relationships is required.
See this SO topic

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The spec anticipates the closing of a database connection with a forced flag.

The spec also mentions some circumstances
where this may occur:

> A connection may be closed by a user agent in exceptional circumstances,
> for example due to loss of access to the file system, a permission change,
> or clearing of the origin’s storage.

Since the latter examples are under the browser's control, this method may
be more useful on the server or for unit-testing.

If the first argument, dbName is missing (or null or undefined),
all connections to all databases will be force-closed.

If the second argument, connIdx is missing (or null or undefined),
all connections with the given name will be force-closed. It can
alternatively be an integer representing a 0-based index to indicate a
specific connection to close.

The third argument msg will be appended to the AbortError that will be
triggered on the transactions of the connection.

Individual IDBDatabase database instances can also be force-closed
with a particular message:

`js
db.__forceClose(msg);
`

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Establishes a connectionQueue for the supplied (or current) origin.

The queue is otherwise only keyed to the detected origin on the
loading of the IndexedDBShim script, though this is usually the
desired behavior.

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The IndexedDB polyfill has sourcemaps enabled, so the polyfill can be debugged
even if the minified file is included.

To print out detailed debug messages, add this line to your script:

`js
shimIndexedDB.__debug(true);
`

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Rather than using globals, a method has been provided to share state across
IndexedDBShim modules.

Configuration can be set early in the non-invasive browser and Node builds
via the second argument to setGlobalVars() (see its definition above).

Its signature (for setting configuration after shimIndexedDB is created) is:

`js
shimIndexedDB.__setConfig({
property: value, property2: value2, ...otherProperties
});
`

or:

`js
shimIndexedDB.__setConfig(property, value);
`

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A utility for creating a DOMException instance. Attempts to use any
available native implementation.

#### Configuration options

The available properties relevant to browser or Node are:

- __DEBUG__ - Boolean (equivalent to calling shimIndexedDB.__debug(val))
- __cacheDatabaseInstances__ - Config to ensure that any repeat
IDBFactory.open call to the same name and version (assuming
no deletes or aborts causing rollbacks) will reuse the same SQLite
openDatabase instance.
- __checkOrigin__ - Boolean on whether to perform origin checks in IDBFactory
methods (open, deleteDatabase, databases); effectively
defaults to true (must be set to false to cancel checks); for Node
testing, you will either need to define a location global from which
the origin value can be found or set this property to false.
- __UnicodeIDStart__ and __UnicodeIDContinue__ - Invocation of
createObjectStore and createIndex calls for validation of key paths.
The specification technically allows all
IdentifierName](https://tc39.github.io/ecma262/#prod-IdentifierName)
strings, but as this requires a very large regular expression,
it is replaced by default with [$A-Z_a-z] and [$0-9A-Z_a-z],
respectively. Note that these are and must be expressed as strings,
not RegExp objects. You can use this configuration to change the default
to match the spec or as you see fit. In the future we may allow the spec
behavior via optional dynamic loading of an internal module.
- __registerSCA__ - For data created in 3.* versions of IndexedDBShim to
continue to work with the more recent version of typeson-registry we
are using (specifically its Structured Cloning Algorithm), set this
property to a callback which is passed the current typeson-registry
structured cloning algorithm representation and return its own to be
passed to typeson.register. See the library
typeson-registry-sca-reverter
for a function that can do this and check it for updates if you are
using it in case needed to work against new updates of IndexedDBShim.
- __fullIDLSupport__ - If set to true, the slow-performing
Object.setPrototypeOf calls required for full WebIDL compliance will
be used. Probably only needed for testing or environments where full
introspection on class relationships is required.
See this SO topic
- __win__, Object on which there may be an openDatabase method (if any)
for WebSQL; Defaults to window or self in the browser and for Node,
it is set by default to node-websql.
If you are intending on adding your own openDatabase implementation,
please note that (for the sake of Node), we rely on supplying an additional
non-WebSQL-standard callback argument to WebSQL transaction or
readTransaction calls in our node-websql fork to allow it to prolong
the transaction (to last through our IndexedDB transaction) and to provide
rollback functionality. (See
, however, for
a remaining issue this fix does not currently overcome.)
- __cursorPreloadPackSize__ - Number indicating how many records to preload for
caching of (non-multiEntry) IDBCursor.continue calls. Defaults to 100.
- __DEFAULT_DB_SIZE__ - Used as estimated size argument (in bytes) to
underlying WebSQL openDatabase calls. Defaults to 4 1024 1024 or
25 1024 1024 in Safari (apparently necessary due to Safari creating
larger files and possibly also due to Safari not completing the storage
of all records even after permission is given). Has no effect in Node
(using node-websql),
and its use in WebSQL-compliant browsers is implementation dependent (the
browser may use this information to suggest the use of this quota to the
user rather than prompting the user regularly for say incremental 5MB
permissions).
- __useSQLiteIndexes__ - Whether to create indexes on SQLite tables (and also
whether to try dropping). Indexes can increase file size and slow
performance on tables involving many write operations, but can speed
performance for retrieval. Defaults to false.
- __avoidAutoShim__ - Where WebSQL is detected but where indexedDB is
missing or poor support is known (non-Chrome Android or
non-Safari iOS9), the shim will be auto-applied without
shimIndexedDB.__useShim(). Set this to true to avoid forcing
the shim for such cases.

The following config are mostly relevant to Node but has bearing on the
browser, particularly if one changes the defaults.

- __addNonIDBGlobals__ - If set to true will polyfill the "global" with
non-IndexedDB shims created by and sometimes returned publicly by
the library. These include ShimEvent, ShimCustomEvent,
ShimEventTarget, ShimDOMException, and ShimDOMStringList.
Mostly useful for debugging (and in Node where these
are not available by default).
- __replaceNonIDBGlobals__ - Similar to addNonIDBGlobals but will attempt
to add the values unprefixed and overwrite if possible. Mostly for
testing.
- __escapeDatabaseName__ - Due to the Node implementation's reliance on
node-websql/node-sqlite3 which create files for each database
(and the fact that we haven't provided an option to map filename-safe
IDs to arbitrary, user-supplied IndexedDB database names),
when the user creates IndexedDB databases, the Node implementation
will be subject to the limitations systems can have with filenames.
Since IndexedDBShim aims to facilitate code that can work on both
the server and client, we have applied some escaping and restrictions
by default. The default behavior is to prefix the database name with
D_ (to avoid filesystem, SQLite, and node-sqlite3 problems if
the user supplies the IndexedDB-permitted empty string database
name), to escape ^ which we use as our own generally-filename-supported
escape character, to escape NUL (which is also problematic in SQLite
identifiers and in node-sqlite3 in general) as ^0, to escape upper-case
letters A-Z as ^A, ^B, etc. (since IndexedDB insists on
case-sensitivity while file systems often do not), to escape any
characters mentioned in databaseCharacterEscapeList (as ^1 + a
two-hexadecimal-digit-padded sequence), and to throw an Error if
databaseNameLengthLimit is not set to false and is surpassed
by the resulting escaped name. You can use this escapeDatabaseName
callback property to override the default behavior, with the callback
accepting a single argument of the user's database name choice and
returning your own filename-safe value. Note that we do escape NUL and
our own escape character (^) before passing in the value (for the
above-mentioned reasons), though you could unescape and
return your own escaped format. While some file systems may not have
the other restrictions, you should at a minimum anticipate
the possibility for empty strings (since we rely on the result of this
function for internal escaping as a SQLite identifier) as well as
realize the string ":memory:" will, if unescaped, have a special
meaning with node-sqlite3. You can make the escaping more lax,
e.g., if your file system is case-sensitive, or you could make it more
stringent.
- __unescapeDatabaseName__ - Not used internally; usable as a convenience
method for unescaping strings formatted per our default escaping
conventions.
- __databaseCharacterEscapeList__ - When this property and
escapeDatabaseName are not overridden, the following characters will
be escaped by default, even though IndexedDB has no such restrictions,
as they are restricted in a number of file systems, even modern,
Unicode-supporting ones: 0x00-0x1F 0x7F " * / : < > ? \ |. This
property can be overridden with a string that will be converted into
an alternate regular expression or supplied with false to disable
any character limitations.
- __databaseNameLengthLimit__ - When this property and
escapeDatabaseName are not overridden, an error will be thrown if
the escaped filename exceeds the length of 254 characters (the shortest
typical modern file length maximum). Provide a number to change the
limit or supply false to disable any length checking.
- __escapeNFDForDatabaseNames__ - Boolean defaulting to true on whether
to escape NFD-escaping characters to avoid clashes on MacOS which
performs NFD on files
- __addSQLiteExtension__ - Boolean on whether to add the .sqlite extension
to database file names (including __sysdb__ which tracks versions);
defaults to true
- __autoName__ - Boolean config to interpret empty string name as a
cue for creating a database name automatically (introspect on
IDBDatabase.name to get the actual name used); false by default

Node-only config:

- __sysDatabaseBasePath__ - Base path for the __sysdb__(.sqlite) database
file; defaults to __databaseBasePath unless another value (including
the empty string) is given; otherwise is the empty string
- __databaseBasePath__ - Base path for user database files; defaults to the
empty string
- __deleteDatabaseFiles__ - Deletes physical database file upon
deleteDatabase (instead of merely emptying). Defaults to true.
Does not currently delete the database for tracking available
databases and versions, __sys__, if emptied; see
#278.
- __memoryDatabase__ - String config to cause all opening, deleting, and
listing to be of SQLite in-memory databases; name supplied
by user is still used (including to automatically build a cache since
SQLite does not allow naming of in-memory databases); the name is also
accessible to IDBFactory.databases(); causes database
name/version tracking to also be within an in-memory database; if
set in the browser, avoids normal database name escaping meant
for Node compatibility; allowable values include the empty string,
":memory:", and file::memory:[?optionalQueryString][#optionalHash].
See and
for more on the function and form of such values

Node config mostly for development debugging:

- __sqlBusyTimeout__ - Integer used by Node WebSQL for
SQLite config
to set the busy timeout
(Defaults to 1000 ms)
- __sqlTrace__ - Callback used by Node WebSQL for
SQLite config
(Invoked when an SQL statement executes, with a rendering of the
statement text)
- __sqlProfile__ - Callback used by Node WebSQL for
SQLite config
(Invoked every time an SQL statement executes)
// Overcoming limitations with node-sqlite3/storing database name on
// file systems
// https://en.wikipedia.org/wiki/Filename#Reserved_characters_and_words

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For retrieving a config value:

`js
shimIndexedDB.__getConfig(property);
`

Known Issues

All code has bugs, and this project is no exception. If you find a bug,
please let us know about it.
Or better yet, send us a fix!
Please make sure someone else hasn't already reported the same bug though.

Here is a summary of main known issues
to resolve:

1. blocked and versionchange IDBVersionChangeEvent event support (#2 and #273) across
processes/browser windows
1. Some issues related to task/micro-task timing
in Node (for inherent limitations in the browser, see below).

There are a few bugs that are outside of our power to fix. Namely:

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While we do try to rollback the database version in the browser when
called for, as we are not able to prolong WebSQL transactions to benefit
from the auto-rollback they perform upon encountering an error (nor
does WebSQL permit manual ROLLBACK commands so that we could undo the
various WebSQL calls we need to make up IndexedDB transactions), we are
not able to provide safe rollbacks in the browser. The synchronous WebSQL
API was not apparently well supported, at least it is missing in Safari
and Chrome, and it would particularly degrade performance in a Node
environment.

The special build of websql that we use does allow such
IndexedDB-spec-compliant (and data-integrity-friendly!) rollback behavior
in Node.

See below on task/micro-task timing for more.

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IndexedDB transactions will timeout
so long as there are no detected active requests.

While a single promise delay (a "microtask") is not supposed to be
long enough to cause a transaction timeout (and they do not in Node
where we have control over extending the transaction), it could possibly
occur in our browser implementation.

(Note that chaining multiple promises or having a long-resolving
promise will likely cause a transaction to expire even in compliant
implementations.)

A setTimeout timeout of 0, on the other hand (a full "task"), ought,
for compliant implementations, to be long enough of a time to cause a
time out of the transaction, but in Node where we prolong transactions
long enough to ensure our full chain of asynchronous SQL needed for the
transaction operations is run (as well as ensure complete rollback should
there be an error causing a transaction abort), it may be too short.

We could fix this in Node (where we can have access to a synchronous
SQLite API such as unlike
on the browser) and ensure transactions finish before the next task
(though always after a microtask), but as mentioned above, this would
degrade performance particularly on a server (and in the browser,
the WebSQL API on which we are relying did not apparently
gain support in browsers for the synchronous API).

This test and
this one
demonstrate the expected timeout behavior with regard to setTimeout
or promises and transaction expiration.

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Due to
certain challenges
in detecting cloneable objects from within JavaScript, there are certain
limitations regarding cloning:

1. We cannot properly detect Proxy to throw upon encountering such
non-cloneable objects
1. Our reliance on Object.prototype.toString to detect uncloneable objects
can fail if that method is overridden or if Symbol.toStringTag is used
to change the default reporting of a given "class".
1. Although they are currently working, we were only able to resolve Blob,
File, and FileList objects synchronously (as
required per spec)
using the now-deprecated XMLHttpRequest synchronous API.
1. Without a means of transferring ArrayBuffer objects in Node, we cannot
meet the requirement to fail upon encountering detached binary objects.
1. They may be other subtleties we have not been able to work around.

We have, however, overcome some cloning issues still faced by browser
implementations, e.g., in Chrome (issue
#698564)
(re: not failing on WeakMap, WeakSet, Promise, and Object.prototype).

We also have limitations in creating certain objects synchronously, namely, the
one method for creating an image bitmap, createImageBitmap, returns a
Promise, so we cannot clone a bona fide image bitmap synchronously so as to
obtain any errors synchronously as expected by the IndexedDB methods involving
cloning.

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Our Mocha test "query multi-entry indexes with hundreds of records" of
IDBIndex/openCursor-spec.js is failing for these versions. Starting
with 9.1.0, however, the test passes again.

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Due to a bug in WebKit, the
window.indexedDB property is read-only and cannot be overridden by
IndexedDBShim. There are two possible workarounds for this:

1. Use window.shimIndexedDB instead of window.indexedDB
1. Create an indexedDB variable in your closure

By creating a variable named indexedDB, all the code within that closure
will use the variable instead of the window.indexedDB property. For
example:

`js
(function () {
// This works on all browsers, and only uses IndexedDBShim as a final fallback
var indexedDB = window.indexedDB || window.mozIndexedDB || // eslint-disable-line no-var
window.webkitIndexedDB || window.msIndexedDB || window.shimIndexedDB;

// This code will use the native IndexedDB, if it exists, or the shim otherwise
indexedDB.open('MyDatabase', 1);
})();
`

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This information might be outdated. Reports on current support or fixes welcome.

IndexedDBShim works on Windows Phone via a Cordova/PhoneGap plug-in. There
are two plugins available: cordova-plugin-indexedDB
and cordova-plugin-indexeddb-async.
Both plug-ins rely on a WebSQL-to-SQLite adapter, but there are differences
in their implementations. Try them both and see which one works best for
your app.

Building

To build the project locally on your computer:

1. __Clone this repo__
If you clone the repository to work against an unstable version, you only
need to clone the repository recursively (via
git clone https://github.com/axemclion/IndexedDBShim.git --recursive)
if you wish to have the W3C tests available for testing (which
unfortunately loads all W3C tests into the "web-platform-tests"
subdirectory rather than just the IndexedDB ones). Otherwise, just use
git clone https://github.com/axemclion/IndexedDBShim.git

1. __Install dev dependencies (and websql for Node)__
yarn install

1. __Run the build script__
npm start

1. __Done__

The output files will be generated in the dist` directory

Upgrading from previous versions

See Versions for migration information.

Testing

See TESTING.

Resources for IndexedDB

- TrialTool - For experimenting with
IndexedDB commands, including predefined examples. (Some examples
may depend on others previously being run, even with
"Load Pre-Requisites" added, but it is nevertheless useful to avoid
boilerplate in testing out commands, in conjunction with
the browser developer tools.)

Contributing

Pull requests or Bug reports welcome! See CONTRIBUTING