The difference is, Chromium and V8 are open source. JScript and J/Direct were not. Apple took KHTML and when it started to fail, forked it into WebKit. Google

The difference is, Chromium and V8 are open source. JScript and J/Direct were not. Apple took KHTML and when it started to fail, forked it into WebKit. Google took WebKit and when it started to fail, forked it into Blink. When IE6 started to fail, the whole industry suffered. (And is now suffering again as Apple refuses to allow any other rendering engine but their failing WebKit port on iOS.)