Very basic and simple table sorter in plain JavaScript

sortable.js

// Sort the rows of a table body by the given column.
function sorttable (table, column) {
  var trs = [];
  var tbody = table.querySelector ('tbody');
  for (var tr of tbody.querySelectorAll ('tr')) {
    trs.push(tr.cloneNode(true));
    tbody.removeChild(tr);
  }
  trs.sort(function(r1 ,r2) {
    var c1 = r1.querySelectorAll('td').item(column).innerText;
    var c2 = r2.querySelectorAll('td').item(column).innerText;
    if (c1 > c2) return 1;
    if (c1 < c2) return -1;
    return 0;
  });
  trs.forEach(tbody.appendChild.bind(tbody));
}
// For the table with the given id make the header elements of a header
// row having the "sortable" class clickable, in order to sort the table
// by the corresponding column. 
function sortable (id) {
  var table = document.getElementById(id);
  for (var th of table.querySelectorAll('thead tr.sortable th')) {
    th.onclick = function (ev) {
      sorttable (table, ev.target.cellIndex);
    };
  }
}