feat: New features and deprecations

[rzane]

This PR intends to deprecate a lot of confusing functionality in this library, and behave more like https://github.com/Betterment/test_track_dart_client.

Changes

Old API (deprecated, but still works)

import TestTrack from 'test_track_js_client';

await TestTrack.initialize();

// Promise<void>
await TestTrack.vary('button_color', {
  context: 'homepage',
  defaultVariant: 'blue',
  variants: {
    blue: () => console.log('blue'),
    red: () => console.log('red')
  }
});

// Promise<void>
await TestTrack.ab('new_feature', {
  context: 'homepage',
  callback: (enabled) => console.log(enabled)
});

New API

import * as TestTrack from 'test_track_js_client';

const testTrack = await TestTrack.initialize();

// string
const color = testTrack.vary('button_color', { context: 'homepage', defaultVariant: 'blue' });
console.log(color)

// boolean
const enabled = testTrack.ab('new_feature', { context: 'homepage' });
console.log(enabled);

Breaking Changes

• Named exports: Use import * as TestTrack or import { initialize } instead of default import
• Web extension: Connecting to the web extension happens when you call initialize() instead of at import-time.

[samandmoore]

domainlgtm platformlgtm