why safari not supporting html 5 datalist

Can you provide an example of when it isn't supporting HTML 5 please?

.... Umm, datalist. It's right there in the title of his question

• http://caniuse.com/#feat=datalist
• https://www.w3.org/wiki/HTML/Elements/datalist
• https://developer.mozilla.org/en-US/docs/Web/HTML/Element/datalist
• http://www.w3schools.com/tags/tag_datalist.asp

This is a user-to-user support community and Apple product teams neither read, nor participate here. They certainly don't share their product plans with us — so only the Apple Safari team knows when datalist support will appear.

You can provide feedback to the Safari Product team here.

For others wondering what datalist is, view this example with a non-Safari browser. Enter the letter 'i' in the input form field to see the datalist appear. The code from this example site only paints the input form field and button, but the drop down datalist feature is inoperable in Safari 10.0.1 on OS X 10.11.6, and macOS Sierra 10.12.1.

Another link with more discussion about datalist.