memory-level

library3.1.0jsnpmunverified

memory-level is an in-memory database implementation that adheres to the `abstract-level` API specification, designed for both Node.js and browser environments. It is currently at version 3.1.0 and is actively maintained, with releases often coinciding with upgrades to its underlying `abstract-level` interface. This package serves as the modern successor to earlier in-memory Level implementations like `memdown` and `level-mem`. A key differentiator is its backing by a fully persistent red-black tree, providing reliable in-memory data storage that supports implicit and explicit snapshots. Unlike disk-backed databases, closing or reopening a `memory-level` instance does not affect its stored data, which is only discarded when all references to the database are released. It offers flexible `storeEncoding` options to optimize for Buffer, Uint8Array, or UTF8 string storage, impacting how data types are handled internally for consistency and performance.

database

npm install memory-level

github ↗package ↗

INSTALL

IMPORT

SIG · MEMORY-LEVEL

memory-level

databasejavascriptv3.1.0

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

MemoryLevel

✓ import { MemoryLevel } from 'memory-level'

✗ import MemoryLevel from 'memory-level'

MemoryLevel is a named export. Attempting to import it as a default export (without curly braces) will result in an error. The package ships TypeScript types.

MemoryLevel

✓ const { MemoryLevel } = require('memory-level')

✗ const MemoryLevel = require('memory-level')

For CommonJS, MemoryLevel is a named export from the module object. Directly requiring the module and expecting the class to be the default export will fail.

MemoryLevelOptions

✓ import type { MemoryLevelOptions } from 'memory-level'

Type import for configuration options when using TypeScript.

Demonstrates initializing an in-memory `MemoryLevel` database, performing basic `put`, `batch`, `get`, and `iterator` operations, and closing the database.

import { MemoryLevel } from 'memory-level' async function runDbExample() { // Create a database with JSON value encoding const db = new MemoryLevel({ valueEncoding: 'json' }) // Add an entry with key 'a' and value 1 await db.put('a', 1) // Add multiple entries using a batch operation await db.batch([{ type: 'put', key: 'b', value: 2 }]) // Get value of key 'a': 1 const valueA = await db.get('a') console.log('Value of key "a":', valueA) // Expected: 1 // Iterate entries with keys that are greater than 'a' console.log('Entries greater than "a":') for await (const [key, value] of db.iterator({ gt: 'a' })) { console.log('Key:', key, 'Value:', value) // Expected: Key: b Value: 2 } // Clean up resources (optional for in-memory, but good practice) await db.close() } runDbExample().catch(console.error);

Debug

Known issues

breaking`memory-level` v3.0.0 upgraded to `abstract-level` v3, introducing breaking changes to the `abstract-level` API. Consult the `abstract-level` migration guide.

fix

Review the `abstract-level` v3 migration guide for updated API signatures and behaviors. Update your database operations accordingly.

affects: >=3.0.0

breaking`memory-level` v2.0.0 upgraded to `abstract-level` v2, bringing breaking changes to the `abstract-level` API.

fix

Refer to the `abstract-level` v2 migration guide for necessary changes in your application's database interactions.

affects: >=2.0.0 <3.0.0

breaking`memory-level` v2.0.0 dropped support for Node.js versions older than 18. Running on unsupported Node.js versions may lead to unexpected behavior or errors.

fix

Upgrade your Node.js environment to version 18 or newer to ensure compatibility and stability.

affects: >=2.0.0

gotchaWhen storing Buffer values, `memory-level` does not copy the Buffer data. Subsequent mutations to the original Buffer object will directly affect the data stored in the database.

fix

If immutability is required for Buffer values, explicitly clone the Buffer before storing it (e.g., `db.put(key, Buffer.from(myBuffer))`).

affects: >=1.0.0

gotchaThe `createIfMissing` and `errorIfExists` options, common in disk-backed `abstract-level` implementations, are not relevant for `memory-level` and will have no effect.

fix

These options can be safely omitted or ignored when creating a `MemoryLevel` instance, as the in-memory nature makes them superfluous.

affects: >=1.0.0

Errors

Common errors & fixes

TypeError: MemoryLevel is not a constructor

Attempting to import MemoryLevel as a default export in ESM (e.g., `import MemoryLevel from 'memory-level'`) or incorrectly requiring in CommonJS (e.g., `const MemoryLevel = require('memory-level')`).

fix

Use named imports for ESM: `import { MemoryLevel } from 'memory-level'`. For CommonJS, use destructuring: `const { MemoryLevel } = require('memory-level')`.

Error [ERR_REQUIRE_ESM]: require() of ES Module .../memory-level/index.js from ... not supported.

Attempting to `require()` memory-level in a CommonJS context when Node.js treats the package as an ES module, or vice-versa with `import` in a CommonJS file. This often occurs in mixed module environments.

fix

Ensure your project's module configuration (`package.json` `type` field or file extensions like `.mjs`/`.cjs`) aligns with how you are importing `memory-level`. For newer projects, consider using ESM throughout. If forced to mix, ensure correct imports for each module system. If using TypeScript, check `tsconfig.json`'s `moduleResolution` and `module` settings.

db.get().on is not a function (or similar error on async methods)

Using older `abstract-level` callback/event-based patterns (e.g., from `leveldown` or `levelup`) with `memory-level` versions that have upgraded to a Promise-based `abstract-level` API (v2+).

fix

Update your code to use the modern Promise-based `async/await` syntax for `get`, `put`, `del`, `batch`, and `iterator` operations as demonstrated in the quickstart, in line with `abstract-level` v2 and v3.

Upgrade

Version history

3.1.0latest on npm

Audit

Dependencies

abstract-levelrequiredCore API interface that memory-level implements. Understanding abstract-level's API is crucial for using memory-level.

functional-red-black-treerequiredUnderlying data structure used for efficient in-memory storage.

Agent activity

6 hits · last 30 days

node

Resources

githubhttps://github.com/Level/memory-level ↗

packagehttps://www.npmjs.com/package/memory-level ↗