@naturalcycles/js-lib/src/web.ts

Standard library for universal (browser + Node.js) javascript

/// <reference lib="es2023" preserve="true" />
/// <reference lib="dom" preserve="true" />

import type { StringMap } from './types.js'

/**
 * Implements WebStorage API by using in-memory storage.
 * Can be useful in SSR environment or unit tests.
 *
 * This is how localStorage can be mocked in Node:
 *
 * Object.assign(globalThis, {
 *  localStorage: new InMemoryWebStorage(),
 * })
 *
 * @experimental
 */
export class InMemoryWebStorage implements Storage {
  constructor(public data: StringMap = {}) {}

  // Not implementing "free property access" now for simplicity,
  // but can be implemented with Proxy
  // [ name: string ]: any

  getItem(key: string): string | null {
    return this.data[key] ?? null
  }

  setItem(key: string, value: string): void {
    this.data[key] = String(value)
  }

  removeItem(key: string): void {
    delete this.data[key]
  }

  key(index: number): string | null {
    return Object.keys(this.data)[index] ?? null
  }

  clear(): void {
    this.data = {}
  }

  get length(): number {
    return Object.keys(this.data).length
  }
}