What is the JavaScript Engine used in Opera Next (Or 12+)

Question

Is it WebKit? Presto? Is V8 engine dedicated to Chrome alone?

Answer 1

WebKit and Presto are not Javascript engines, but rendering engines. Opera previously used a Javascript engine called "Carakan", but have since started transitioning from Presto and Carakan to Blink and V8.

Answer 2

As per wikipedia:

It remained in use until Opera 12.15, when the browser's developer Opera Software ASA began phasing Presto out of its products in favor of the WebKit layout engine and V8 JavaScript engine combined with a modified Chromium browser.

For more , you can go through Web specifications support in Opera Presto 2.12.