* Refactored existing cache

* Renamed to InMemoryCache
* Removed default export
* Added ICache
* Refactored tests
* Auth0Client now uses ICache instead of implemented cache type

* Added ability to configure cache strategy

* Added VS Code debug configuration for running tests

* Implemented local storage cache

* Made use of "in" to check presence of key in object

* Refactored playground page to use Vue + Bootstrap

* Added ability to clear the token cache

Added clear() to the ICache interface, meaning that this had to be
applied to the memory and localstorage caches.

Made use of jest-localstorage-mock package for easier testing with
localstorage, making the clear method easier to test for the
LocalStorageCache implementation.

* Revamped the playground page with Vue and Bootstrap additions

* Vulnerable dependency update

* Added a section in the readme about the caching strategy

* Fixed integration tests

* Readme wording

* Refactored how items are cleared from local storage

* Refactored cache key

* Readme tweak to make what 'data' is more clear

* Renamed cacheStrategy option to cacheLocation

* Cache now includes client_id in key

* Refactored getting token using iframe into its own method

* Implemented getTokenUsingRefreshToken

* Fixed up the playground page to support refresh tokens

* Set offline_access scope during initialization

* Added error condition for when a refresh token isn't stored or no cache exists

* Removed specification of audience when calling token endpoint

* Clarified docs on useRefreshTokens

* Simplified usage of getUniqueScopes in index.ts

* Fixed some playground syntax issues for IE11

* Playground now shows auth info on load if authenticated

* Simplified integration tests

* Added more integration tests around getting access tokens

* Encoded the nonce value when building authorize URLs

* Renamed encodeState to encode

* Fixed broken integration test

* Release 1.7.0-beta.1

* Tweaked intermittently-failing test

* Fixed issue with cache not retaining refresh token

* Fix integration tests

* Removed unused core-js import

* Extracted 1 day in seconds value to a constant

* Applied comment to be consistant with related test

* Applied brace styling for consistancy

* Reworked expiry tests to mock date instead of using negative exp

* Added some comments to the cache tests to explain the test scenario

* Cleaned up JS return statement styling

…ead (#354)

* Removed setTimeout cache expiry in favour of expiry-on-read

* Replace magic values with a constant

* Added retry logic to getJSON

* Moved retry count to a constant

* Reverted changes to oauthToken

* Reduced retry count to 3

* Implemented a timeout around the fetch call

* Made the fetch timeout a default value and adjusted tests

* Fixed broken test after merge

* Implemented AbortController to abort fetch on timeout

* Added abortcontroller polyfill

* Created factory function for AbortController to be mocked and tested

…hen using local storage (#352)

* Changes to the initialization strategy

* Removed unused import from a test

`// @ts-ignore` comment is not preserved in the generated type definition, which means that library ships broken type definitions and consumers will get an error when they attempt to use it.

Reproduction:

```
$ npm i @auth0/[email protected] typescript
$ cat index.ts
import c from '@auth0/auth0-spa-js';
$ ./node_modules/.bin/tsc --noEmit index.ts
node_modules/@auth0/auth0-spa-js/dist/typings/index.d.ts:9:8 - error TS2440: Import declaration conflicts with local declaration of 'Auth0Client'.

9 import Auth0Client from './Auth0Client';
         ~~~~~~~~~~~

Found 1 error.
```

#364)

* Logic falls back to the iframe method when no refresh token is found

* Cleaned up a variable name

* Updated integration test

This includes the reversion of the Auth0Client constructor feature.

Export constructor

* Ran npm audit fix

* Updated packages within semver

* Updated typedoc

* Updated rollup to 2.3.3 + plugins

* Updated idtoken-verifier to 2.0.2

* Fixed warnings on async describe blocks

* Updated prettier/pretty-quick

* Updated Husky and ran husky-upgrade

* Updated Cypress, wait-on and concurrently

* Upgraded tslint

* Updated circle image

* fetch in a web worker

* token worker

* known issue: doesn't work if user already logged in (need authorization_code grant_type to populate the refresh token)

* add iframe fallback

* fix tests

* We want to load:
`rollup-plugin-worker-loader::module:./token.worker.ts`
But not:
rollup-plugin-worker-loader::module:/Users/adammcgrath/dev/auth0-spa-js/src/token.worker.ts
TODO: check windows

* Fixed ES5 transpilation for rollup worker plugin

* Make messages serializable using `JSON.parse(JSON.stringify({}))`
Swap imports per https://github.com/mo/abortcontroller-polyfill/blob/3f1c13d2e4087ee15ded81786f1110ae547931bb/README.md#using-it-on-internet-explorer-11-msie11

* only use worker for non ie, local refresh token opts

TODO: fix tests

* Fix tests

* Removed refresh token from worker memory when not included in response

* Moved offline_access scope configuration to constructor

* Modified playground to use both factory func and constructor

* Remove Object.assign

* Remove checks to fix rebuild issue

* Abort timed out requests in the Web Worker

* Errors

* Fix tests

* Add some more tests

* DRY up the tests a little

* Moar tests

* unused import

* update rollup-plugin-web-worker-loader
don't run `addEventListener` in tests
add test for missing refresh token and localstorage

* add timeout tests

* add browser tests

* Only include files in the typings copy process

* Fix fallback logic when no RT and no worker

* add browser tests and comments

* bump node version in Jenkinsfile

* Removed unused import

* Added sanity check for web worker support

* Fixed tests for window.Worker check

* Moved constructor tests into Auth0Client

Co-authored-by: Steve Hobbs <[email protected]>

If the iframe is removed from the DOM prior to the timeout it would error on removeChild.

Error thrown: `Uncaught DOMException: Failed to execute 'removeChild' on 'Node': The node to be removed is not a child of this node.`

Bug introduced in #376

Co-authored-by: Steve Hobbs <[email protected]>

When the iframe is closed, the source of the event message is null, resulting in an error: Cannot read property 'close' of undefined (Chrome).

Co-authored-by: Steve Hobbs <[email protected]>