index.js

const Loki = require('lokijs') // Used as the high-performance store, and clears when the nodejs process restarts
const crypto = require('crypto') // Used for creating a hashed name for cache in case the nodejs project already uses lokijs as a store/database

// Returns a ExtremeCache object (in a certain sense, its a stateless class)
module.exports = ExtremeCache

function ExtremeCache (cacheName) {
  // ------- Global class wide variables -------
  this.hashedName = (cacheName) => {
    if (!cacheName) throw new Error('Please provide a cache name. Example: ` ExtremeCache("my-custom-cache") ` ') // If no input is given, throw error
    return crypto.createHash('sha256').update(cacheName).digest('hex') // Create hashed name for cache in case project already uses lokijs as a store/database
  }
  this.cache = new Loki(`${this.hashedName(cacheName)}.db`) // Create temporary cache upon initialisation
  this.store = this.cache.addCollection(this.hashedName(cacheName), { clone: true, disableMeta: true }) // Set clone to true to prevent changing store values from resultset, and set disableMeta to true to disable Metadata

  // ------- Set value from store using key -------
  this.set = (key, value, expiryInMs) => {
    try {
      if (!key) throw new Error('Please provide a key name. Example: ` .set("car-name", "honda") ` ')
      if (!value) throw new Error('Please provide a value name. Example: ` .set("car-name", "honda") ` ')
      let objectToInsert = { key: key, value: value, expiryInMs: expiryInMs }
      this.store.insert(objectToInsert)
      if (expiryInMs) { // Set expiry to key-value pair. If no expiry is provided, the key-value pair will not expire.
        setTimeout(() => {
          this.store.findAndRemove({ key: key })
        }, expiryInMs)
      }
      return objectToInsert // Returns object that has been created
    } catch (error) {
      throw error
    }
  }

  // ------- Get value from store using key -------
  this.get = (key) => {
    try {
      return (this.store.find({ key: key })[0] || {}).value // Returns undefined if not found, else returns object value.
    } catch (error) {
      throw error
    }
  }

  // ------- Delete value from store using key -------
  this.delete = (key) => {
    try {
      let removedObjectValue = (this.store.find({ key: key })[0] || {}).value
      this.store.findAndRemove({ key: key })
      return { key: key, value: removedObjectValue } // Returns undefined if object to be deleted doesn't exist, else return object that has been deleted.
    } catch (error) {
      throw error
    }
  }

  // ------- Dump entire store -------
  this.dump = () => {
    try {
      return this.store.find().map((item) => {
        delete item['$loki']
        return item
      }) // Returns the entire cache as an array. If there are no items in the cache it will return an empty array.
    } catch (error) {
      throw error
    }
  }

  // ------- Wipe the store -------
  this.clearAll = () => {
    try {
      this.store.clear()
      return cacheName // Returns the name of the cleared cache.
    } catch (error) {
      throw error
    }
  }
}