how to set id of element in jquery code example

Example 1: store id of an element jquery

$(". only_this_class"). click(function() { var clickedId= $(this). attr("id"); alert(clickedId); });

Example 2: add id in jquery

TO add dynamically:
let $id=0;
$('ul li').each(()=>{
///use this also $('ul').children("li").each(function()=>{/// same below code})
  ///this will select the element under current selection, 
  ///THis outside the function relates or selects body, inside the function 
  /// denotes the selector php and js in think all library may be syntax 
  ///get vary
  $(this).attr('id','id'+$id)
  $i=$i+1
})
using js
///place the script just above to </body>
const s=document.getElementsByTagName('li');
len=s.length;
console.log(len)
for(let i=0;i<len;i++){
  s[i].id="id"+i;
}