A simple file-based cache driver for Node with expiration-support. No external packages needed.

node-disk-cache.js

import fs from 'fs';

export default class DiskCache {
  static basePath = './.cache';
  static prettyPrintJson = false;
  #filePath;
  #cacheName;
  #data = {};

  constructor(cacheName) {
    this.#cacheName = cacheName ?? 'default-cache';
    return this.#readFile(); 
  }

  get(key) {
    const data = this.#data?.[key];
    if (data) {
      if (this.#isExpired(data)) {
        this.delete(key);
      } else {
        return data.value;
      }
    }
  }

  put(key, value, ttl) {
    const expiration = (ttl && Number.isInteger(ttl)) ? this.#unixTimestamp() + ttl : false;
    this.#data[key] = { value, expiration  };
    return this.#writeFile();
  }

  delete(key) {
    try {
      delete this.#data[key];
      return this.#writeFile();
    } catch(e) {
      return false;
    }
  }

  getData() {
    return this.#data;
  }

  #getFilePath() {
    if (!this.#filePath) {
      this.#filePath = `${DiskCache.basePath}/${this.#cacheName}.json`;
    }
    return this.#filePath;
  }

  #ensureFileExists() {
    const filePath = this.#getFilePath();
    if (!fs.existsSync(filePath)) {
      fs.closeSync(fs.openSync(filePath, 'w'));
    }
  }

  #writeFile() {
    try {
      this.#ensureFileExists();
      const filePath = this.#getFilePath();
      fs.writeFileSync(filePath, JSON.stringify(this.#data, null, DiskCache.prettyPrintJson ? 4 : 0), 'utf8');
      return true;
    } catch(e) {
      return false;
    }
  }

  #readFile() {
    try {
      this.#ensureFileExists();
      const filePath = this.#getFilePath();
      this.data = JSON.parse(fs.readFileSync(filePath, 'utf8'));
      return true;
    } catch(e) {
      return false;
    }
  }

  #unixTimestamp() {  
    return Math.floor(Date.now() / 1000);
  }

  #isExpired(data) {
    return Number.isInteger(data?.expiration) && data?.expiration <= this.#unixTimestamp();
  }
}