level-js

by Level

Level / level-js

An abstract-leveldown compliant store on top of IndexedDB.

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level-js

An

abstract-leveldown
compliant store on top of IndexedDB.

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Table of Contents

Click to expand

Background

Here are the goals of

level-js
:
  • Store large amounts of data in modern browsers
  • Pass the full
    abstract-leveldown
    test suite
  • Support string and
    Buffer
    keys and values
  • Be as fast as possible
  • ~~Sync with multilevel over ASCII or binary transports.~~

Being

abstract-leveldown
compliant means you can use many of the Level modules on top of this library.

Example

If you are upgrading: please see UPGRADING.md.

var levelup = require('levelup')
var leveljs = require('level-js')
var db = levelup(leveljs('bigdata'))

db.put('hello', Buffer.from('world'), function (err) { if (err) throw err

db.get('hello', function (err, value) { if (err) throw err

console.log(value.toString()) // 'world'

}) })

In ES6 browsers:

const levelup = require('levelup')
const leveljs = require('level-js')
const db = levelup(leveljs('bigdata'))

await db.put('hello', Buffer.from('world')) const value = await db.get('hello')

Browser Support

Sauce Test Status

Type Support

Keys and values can be a string or

Buffer
. Any other type will be irreversibly stringified. The only exceptions are

null
and
undefined
. Keys and values of that type are rejected.

In order to sort string and Buffer keys the same way, for compatibility with

leveldown
and the larger ecosystem,
level-js
internally converts keys and values to binary before passing them to IndexedDB. If binary keys are not supported by the environment (like IE11)
level-js
falls back to
String(key)
.

If you desire non-destructive encoding (e.g. to store and retrieve numbers as-is), wrap

level-js
with
encoding-down
. Alternatively install
level
which conveniently bundles
levelup
,
level-js
and
encoding-down
. Such an approach is also recommended if you want to achieve universal (isomorphic) behavior. For example, you could have
leveldown
in a backend and
level-js
in the frontend. The
level
package does exactly that.

When getting or iterating keys and values, regardless of the type with which they were stored, keys and values will return as a Buffer unless the

asBuffer
,
keyAsBuffer
or
valueAsBuffer
options are set, in which case strings are returned. Setting these options is not needed when
level-js
is wrapped with
encoding-down
, which determines the optimal return type by the chosen encoding.
db.get('key', { asBuffer: false })
db.iterator({ keyAsBuffer: false, valueAsBuffer: false })

Install

With npm do:

npm install level-js

Not to be confused with leveljs.

This library is best used with browserify.

API

db = leveljs(location[, options])

Returns a new

leveljs
instance.
location
is the string name of the
IDBDatabase
to be opened, as well as the object store within that database. The database name will be prefixed with
options.prefix
.

options

The optional

options
argument may contain:
  • prefix
    (string, default:
    'level-js-'
    )
    : Prefix for
    IDBDatabase
    name.
  • version
    (string | number, default:
    1
    )
    : The version to open the database with.

See

IDBFactory#open
for more details.

Running Tests

git clone [email protected]:Level/level-js.git
cd level-js
npm install
npm test

It will print out a URL to open in a browser of choice.

Big Thanks

Cross-browser Testing Platform and Open Source ♥ Provided by Sauce Labs.

Sauce Labs logo

Contributing

Level/level-js
is an OPEN Open Source Project. This means that:

Individuals making significant and valuable contributions are given commit-access to the project to contribute as they see fit. This project is more like an open wiki than a standard guarded open source project.

See the Contribution Guide for more details.

Donate

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Level
and its activities, become a backer or sponsor on Open Collective. Your logo or avatar will be displayed on our 28+ GitHub repositories and npm packages. 💖

Backers

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Sponsors

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License

MIT © 2012-present Max Ogden and Contributors.

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