level-supports

library6.2.0jsnpmunverified

level-supports is a utility package within the LevelDB ecosystem designed to generate a manifest object detailing the capabilities of an `abstract-level` database instance. This manifest allows consumers of a database to programmatically check for specific features, such as `permanence`, `encodings` (like `utf8`), `implicitSnapshots`, `explicitSnapshots`, and `has` (for `has()` and `hasMany()`). The current stable version is 6.2.0. Releases are typically driven by new `abstract-level` features or Node.js compatibility updates, with a focus on semantic versioning for breaking changes. Its key differentiator is providing a standardized, merged, and enriched feature description, moving beyond simple boolean checks to handle more complex truthy values for future extensibility.

database

npm install level-supports

github ↗package ↗

INSTALL

IMPORT

SIG · LEVEL-SUPPORTS

level-supports

databasejavascriptv6.2.0

Install

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Import

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Disk

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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.

supports

✓ import { supports } from 'level-supports'

✗ const supports = require('level-supports')

Since v3.0.0, 'level-supports' exports a named 'supports' function, not a default export. CommonJS 'require' still works, but ESM import is preferred in modern Node.js environments.

supports

✓ const { supports } = require('level-supports')

This is the correct CommonJS pattern for named exports. Prior to v3.0.0, it was a default export accessed as `const supports = require('level-supports')`.

Manifest

✓ import type { Manifest } from 'level-supports'

TypeScript type for the manifest object is available for better type safety when defining custom manifests or consuming the generated one.

Demonstrates how to create a support manifest, attach it to a database object, and check for specific features like permanence, encodings, and `has()`.

import { supports } from 'level-supports'; // Simulate a database with specific capabilities const myCustomDb = { // In a real scenario, these would come from the database driver supports: supports({ permanence: true, encodings: { utf8: true, json: { value: true, array: false }, binary: {} // Truthy, details allowed }, implicitSnapshots: true, explicitSnapshots: false, has: true }) }; console.log(`Database supports permanence: ${!!myCustomDb.supports.permanence}`); console.log(`Database supports JSON encoding: ${!!myCustomDb.supports.encodings.json}`); if (myCustomDb.supports.has) { console.log('Database implements has() and hasMany().'); } else { console.log('Database does not implement has().'); } // Merge with another manifest (e.g., from a plugin) const pluginManifest = { signals: true }; const mergedSupports = supports(myCustomDb.supports, pluginManifest); console.log(`Database supports signals (after merge): ${!!mergedSupports.signals}`);

Debug

Known issues

breakingVersion 6.0.0 dropped support for Node.js versions older than 16. Ensure your environment meets this requirement.

fix

Upgrade your Node.js environment to version 16 or newer. If you need to support older Node.js versions, pin 'level-supports' to '~5.x'.

affects: >=6.0.0

breakingVersion 5.0.0 removed properties that were implicitly true since 'abstract-level@1'. This streamlines the manifest, focusing on explicit feature declarations.

fix

Review your manifest creation and usage. If you were relying on implicit truths for older properties, you might need to explicitly define them if still required, though most were redundant with `abstract-level@1`.

affects: >=5.0.0

breakingVersion 3.0.0 introduced significant breaking changes: it is no longer compatible with `abstract-leveldown` or `levelup` directly, and it changed from a default export to a named export (`{ supports }`). Additionally, `encodings` and `events` properties are now always objects.

fix

Update import statements from `const supports = require('level-supports')` to `const { supports } = require('level-supports')` or `import { supports } from 'level-supports'`. Ensure your database implementations are `abstract-level` compatible. Adjust manifest property checks for `encodings` and `events` to expect objects.

affects: >=3.0.0

gotchaManifest properties are truthy rather than strictly boolean. When checking for support, always use `if (db.supports.feature)` instead of `if (db.supports.feature === true)` to accommodate future extensibility where features might have object values.

fix

Adopt the `if (db.supports.feature)` pattern for all feature checks to ensure forward compatibility.

affects: *

deprecated`implicitSnapshots` is aliased as `snapshots` for backwards compatibility. While `snapshots` still works, `implicitSnapshots` is the preferred and more descriptive property name.

fix

Update code referencing `db.supports.snapshots` to `db.supports.implicitSnapshots` for clarity and future-proofing.

affects: >=6.1.0

Errors

Common errors & fixes

TypeError: (0, level_supports_1.default) is not a function

Attempting to use `level-supports` v3.0.0 or higher with a default import/require syntax, but the package changed to a named export.

fix

Change your import statement from `import supports from 'level-supports'` to `import { supports } from 'level-supports'` or for CommonJS, `const supports = require('level-supports')` to `const { supports } = require('level-supports')`.

Error: Persistent storage is required

A consumer of the database is checking for `db.supports.permanence` but the provided manifest or underlying database driver indicates `permanence: false`.

fix

Ensure that the `level-supports` manifest accurately reflects the underlying database's capabilities, especially for critical features like `permanence`. If persistence is required, use a database that provides it or configure the manifest accordingly.

Upgrade

Version history

6.2.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

13 hits · last 30 days

node

Resources

githubhttps://github.com/Level/supports ↗

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