backup memex data using chrome snippet.

backup.js

var dbName = 'memex';
var version = 1;

var conn = indexedDB.open(dbName, version) // change the name and version as needed

function exportToJson(idbDatabase) {
  return new Promise((resolve, reject) => {
    const exportObject = {}
    if (idbDatabase.objectStoreNames.length === 0) {
      resolve(JSON.stringify(exportObject))
    } else {
      const transaction = idbDatabase.transaction(
        idbDatabase.objectStoreNames,
        'readonly'
      )

      transaction.addEventListener('error', reject)

      for (const storeName of idbDatabase.objectStoreNames) {
        const allObjects = []
        transaction
          .objectStore(storeName)
          .openCursor()
          .addEventListener('success', event => {
            const cursor = event.target.result
            if (cursor) {
              // Cursor holds value, put it into store data
              allObjects.push(cursor.value)
              cursor.continue()
            } else {
              // No more values, store is done
              exportObject[storeName] = allObjects

              // Last store was handled
              if (
                idbDatabase.objectStoreNames.length ===
                Object.keys(exportObject).length
              ) {
                resolve(JSON.stringify(exportObject))
              }
            }
          })
      }
    }
  })
}

conn.onsuccess = e => {
  var database = e.target.result
  exportToJson(database).then(console.log).catch(console.error)
}