PHP - 输入标记上的自动完成

Google has an autofill function on any website. I wonder if it is possible if you could recreate this on your own website (eg. Autofill when website is loading). I want this autofill function implemented on my website. The data it gets should be coming from a database. What would be the most efficient way to be doing this?

The Value Attribute = What is physically in the input box

The Placeholder Attribute = An input hint, as soon as a user types in the input box it disapears.

Use them like:

<input type="text" value="<?=$data['username']>">

Or: ">

Also, disable autofill with autocomplete="off"

Source for autocomplete