Simple get/set key value store for SvelteKit, etc.

example.ts

const keyValueStore = new KeyValueStore('./key-value-store.txt');

// Get a value from the store
const value = await keyValueStore.get('key1');

// Set a value in the store
await keyValueStore.set('key2', 'value2');

keystore.ts

import fs from 'fs';

export class KeyValueStore {
  private filePath: string;

  constructor(filePath: string) {
    this.filePath = filePath;
  }

  public async get(key: string): Promise<string | undefined> {
    try {
      const data = await fs.promises.readFile(this.filePath, 'utf-8');
      const keyValuePairs = data.split('\n');
      const keyValuePair = keyValuePairs.find((pair) => pair.startsWith(key));
      if (keyValuePair) {
        return keyValuePair.split(':')[1];
      }
      return undefined;
    } catch (error) {
      return undefined;
    }
  }

  public async set(key: string, value: string): Promise<void> {
    try {
      const data = await fs.promises.readFile(this.filePath, 'utf-8');
      const keyValuePairs = data.split('\n');
      const existingKeyValuePair = keyValuePairs.find((pair) => pair.startsWith(key));
      if (existingKeyValuePair) {
        const newKeyValuePairs = keyValuePairs.filter((pair) => pair !== existingKeyValuePair);
        newKeyValuePairs.push(`${key}:${value}`);
        await fs.promises.writeFile(this.filePath, newKeyValuePairs.join('\n'), 'utf-8');
      } else {
        await fs.promises.appendFile(this.filePath, `${key}:${value}\n`, 'utf-8');
      }
    } catch (error) {
      console.error(error);
    }
  }
}