How do I make a submit through AJAX? I created a webform in Drupal 8. While submitting the form, it reloads the whole page, even I had selected inline submission in confirmation message.
Just checked your issue by upgrading Webform to version 8.x-5.0-beta15. After enabling AJAX on the form and setting the confirmation to either inline or message the confirmation worked as expected. I did needed to clear my cache though.

So try upgrading the Webform module and clear your cache.