js remove child elements

1function deleteChild() { 
2        let e = document.querySelector("ul"); 
3        
4        //e.firstElementChild can be used. 
5        let child = e.lastElementChild;  
6        while (child) { 
7            e.removeChild(child); 
8            child = e.lastElementChild; 
9        } 
10    } 
11    let btn = document.getElementById( 
12    "btn").onclick = function() { 
13        deleteChild(); 
14    }