Add CSS transition for modal entering and exiting.

[tienpv222]

Provide a general summary of the feature here

Similar to how modal is handling animation, we can use transitionstart and transitionend to support CSS transition. This is suitable for those who prefer to animate using CSS transition.

🤔 Expected Behavior?

data-entering and data-exiting can also be tied to CSS transition, or a pair of new data attributes if clarification is needed.

😯 Current Behavior

Devs can only style modal through animation.

💁 Possible Solution

No response

🔦 Context

I was writing a small helper to style Tooltip using CSS transition, and wondered if it should be included in the core. Since it's aligned with the existing support for animation, maybe it's reasonable to have it built-in too.

💻 Examples

No response

🧢 Your Company/Team

No response

🕷 Tracking Issue

No response

[LFDanLu]

The team thinks that managing transitions would be a pretty large undertaking, perhaps an external library could help with this? We haven't looked into this yet so it would take some investigation.