mock-storage

library1.1.0jsnpmunverified

A lightweight in-memory mock implementation of the Web Storage API (Storage interface) for testing. Version 1.1.0. Fully compliant with TypeScript's Storage interface, uses ES2015 Proxy and Map. Ideal for unit testing localStorage/sessionStorage in Node.js or browser environments without side effects. Differentiates from alternatives like jest-localstorage-mock by being pure TypeScript with a simple API.

testing

npm install mock-storage

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · MOCK-STORAGE

mock-storage

testingjavascriptv1.1.0

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

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

mockStorage

✓ import { mockStorage } from 'mock-storage'

✗ const mockStorage = require('mock-storage')

Library is ESM-only. CommonJS require will fail.

Storage

✓ import type { Storage } from 'mock-storage'

✗ import { Storage } from 'mock-storage'

Storage is exported as a type only, not a value. Use type import to avoid runtime errors.

default import

✓ import { mockStorage } from 'mock-storage'

✗ import mockStorage from 'mock-storage'

No default export exists. Named import is required.

Demonstrates creating a mock storage instance, setting/getting items, using property access, TypeScript type, and initializing with data.

import { mockStorage } from 'mock-storage'; // Create a mock storage instance const storage = mockStorage(); // Set and get items storage.setItem('foo', 'bar'); console.log(storage.getItem('foo')); // 'bar' // Use property access (Proxy-based) storage.baz = 'qux'; console.log(storage.baz); // 'qux' // Works with TypeScript's Storage type const typedStorage: Storage = mockStorage(); // Optionally initialize with a Map const initialData = new Map<string, string>([['key', 'value']]); const preloadedStorage = mockStorage(initialData); console.log(preloadedStorage.getItem('key')); // 'value'

Debug

Known issues

gotchaProperty access (e.g., storage.foo) may not work if the environment lacks ES2015 Proxy support (e.g., older Node versions, some test runners).

fix

Use explicit setItem/getItem methods instead of property access, or ensure Proxy polyfill is available.

affects: >=1.0.0

gotchaThe library is ESM-only. Using require() will throw an error.

fix

Use import syntax or configure your test framework to support ESM (e.g., use --experimental-vm-modules in Node, or transform in Jest).

affects: >=1.0.0

gotchamockStorage() with no arguments creates an empty storage; passing a Map<string, string> overwrites any existing default data.

fix

To add to existing data, pass a Map containing the desired initial entries.

affects: >=1.0.0

Errors

Common errors & fixes

ERR_REQUIRE_ESM: require() of ES Module

Using CommonJS require() on an ESM-only package.

fix

Replace require with import: import { mockStorage } from 'mock-storage'

TypeError: storage.foo is not a function

Trying to use property access on a storage instance that doesn't support Proxy (older Node).

fix

Use setItem/getItem instead: storage.setItem('foo', 'bar')

TypeError: Class extends value #<Object> is not a constructor or null

Importing Storage as a value instead of a type.

fix

Use type-only import: import type { Storage } from 'mock-storage'

Upgrade

Version history

1.1.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

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Resources

githubhttps://github.com/TylorS/mock-storage ↗

packagemock-storage ↗

homepagehttps://github.com/TylorS/mock-storage#readme ↗