Сортировать таблицу по подстроке

function sortTable(tbody, col, asc){
    var rows = tbody.rows;
    var rowsLen = tbody.rows.length;
    var arr = new Array();
    var i, j, cells, cellLen;
    // fill the array with values from the table
    for(i = 0; i < rowsLen; i++){
    cells = rows[i].cells;
    cellLen = cells.length;
    arr[i] = new Array();
        for(j = 0; j < cellLen; j++){
          arr[i][j] = cells[j].innerHTML;
        }
    }
    //short the array
    arr.sort(function(a, b){
       //this is your use case.sort the data in array after spilt.
       var aCol=a[col].split("-")[1];
       var bCol=b[col].split("-")[1];
       return (aCol == bCol) ? 0 : ((aCol > bCol) ? asc : -1*asc);
    });
    
    for(i = 0; i < rowsLen; i++){
        arr[i] = "<td>"+arr[i].join("</td><td>")+"</td>";
    }
    tbody.innerHTML = "<tr>"+arr.join("</tr><tr>")+"</tr>";
}
var tbody=document.getElementById("myTable2Tbody");
sortTable(tbody,1, 1);
//for asc use 1,for dsc use -1

<table id  = "myTable2">
    <thead>
        <tr>
            <th>Teacher</th>
            <th>Course Number</th>
        </tr>
    </thead>
    <tbody id  = "myTable2Tbody">
        <tr>
            <td>Smith</td>
            <td>CS-301</td>
        </tr>
        <tr>
            <td>Kelly</td>
            <td>CX-201</td>
        </tr>
        <tr>
            <td>Park</td>
            <td>CS-001</td>
        </tr>        
    </tbody>
</table>

var tbody = document.querySelector('#myTable2 tbody')
var trs = tbody.querySelectorAll('tr')

var sorted = [...trs].sort((tra, trb) => {
    var courseA = tra.querySelectorAll('td')[1].innerText
    var courseB = trb.querySelectorAll('td')[1].innerText

    return courseA.split('-')[1] - courseB.split('-')[1]
})

tbody.innerHTML = '';
sorted.forEach(tr => tbody.appendChild(tr))

<table id = "myTable2">
    <thead>
        <tr>
            <th>Teacher</th>
            <th>Course Number</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>Smith</td>
            <td>CS-301</td>
        </tr>
        <tr>
            <td>Kelly</td>
            <td>CX-201</td>
        </tr>
        <tr>
            <td>Park</td>
            <td>CS-001</td>
        </tr>
    </tbody>
</table>