metamask-extension/ui/lib/storage-helpers.js

import localforage from 'localforage'

export async function getStorageItem(key) {
  try {
    const serializedData = await localforage.getItem(key)
    if (serializedData === null) {
      return undefined
    }

    return JSON.parse(serializedData)
  } catch (err) {
    return undefined
  }
}

export async function setStorageItem(key, value) {
  try {
    const serializedData = JSON.stringify(value)
    await localforage.setItem(key, serializedData)
  } catch (err) {
    console.warn(err)
  }
}