Proxy for localStorage that prefixes all keys.

prefixed-localstorage.js

const prefix = 'prefix_'
const rawLS = window.localStorage
const wrappedLS = new Proxy(rawLS, {
  get(target, prop, receiver) {
    if (typeof target[prop] === 'function') {
      return function(key, value) {
        return target[prop](prefix + key, value)
      }
    }

    return target[prefix  + prop]
  },
  set(target, prop, value) {
    target[prefix + prop] = value
    return true
  },
  deleteProperty(target, prop) {
    delete target[prefix + prop]
    return true
  },
  has(target, prop) {
    return (prefix + prop) in target
  },
  ownKeys(target) {
    return Object.keys(target).filter(it => it.startsWith(prefix)).map(it => it.substring(prefix.length))
  },
  enumerate(target) {
    return Object.keys(target).filter(it => it.startsWith(prefix)).map(it => it.substring(prefix.length))
  },
  getOwnPropertyDescriptor(target, prop) {
    const val = target[prefix + prop]
    return val ? {
      value: val,
      writable: true,
      enumerable: true,
      configurable: true
    } : undefined
  }
})
Object.defineProperty(window, 'localStorage', { value: wrappedLS })