Edit in JSFiddle

function go (){
   function reverse(arr){
        if (arr.length <= 1)
            return arr;
        else
            return reverse(arr.slice(1)).concat([arr[0]]);
   }
    
   var arr = [1, 2 , 3, 4, 5];
   
   var before = document.getElementById('before');
   before.innerHTML = arr;

   var after = document.getElementById('after');
   after.innerHTML = reverse(arr);   
}

<h1 id="title">Reverse</h1>
<input type="submit" id="byBtn" value="Go" onclick="go()"/>
<p id="before" />
<p id="after" />