The BrowserGet function allows you to discern the browser in which it is running with moderately reasonable certainty - at least as of this writing.
The IDs it returns are as follows:
| Unknown | 0 |
| Chrome | 1 |
| Chromium | 2 |
| Edge | 4 |
| IE | 8 |
| Safari | 16 |
| Opera | 32 |
| Firefox / Waterfox | 64 |