iOS 10 Safari JavaScript setting disabled Today, JavaScript in Safari suddenly stopped functioning. I had just updated my iPhone 6s to iOS 10 yesterday. I eventually noticed that somehow, JavaScript had been disabled in the Safari settings. Furthermore, the control itself is disabled!



Why might javascript be permanently disabled? How can I re-enable it?

It obviously makes it difficult to debug javascript when it's disabled on my debug device.
The following is based on my observation.

By default the Safari JavaScript is enabled, because most of the website that I visited that extensively using JavaScript are working in Safari. The problem starts only when I Clear History and Website Data and go to Settings &gt; Safari &gt; Advanced.

I think as soon as you hit Advanced "for the first time" the program just has an issue as no previous settings are set, thus setting itself to Disable.

I exited from settings and visit the previous website that are using JavaScript, obviously all of them either don't show up or become a Dumb website except you click a link that uses anchor. 

Solution: Just go to Advanced again and set Enable the JavaScript setting. Next time you visit this remain enabled.