input radio selected by default code example
Example 1: default checked radio button
<input type="radio" name="imgsel" value="" checked>
Example 2: html radio button checked
<input type="radio" id="huey" name="drone" value="huey"
checked>
<!-- https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/radio-->
Example 3: radio by default selected
checked="checked"