the DOM doesn’t work with me when I try to sort an element

here is the file I have. when I try to sort some number it doesn’t change and keeps empty

HTML file

<tr>
<th>Original array</th>
<td id ="td1">1,5,7,-1,3</td></tr>
<tr>
<th>Sorted Array</th>
<td id="td2"></td>

JS file

var OriginalArr = document.getElementById("td1").value;
var a =  document.getElementById("td2").value;
a.value = Original.sort();