冻结表中已呈现列的宽度

window.onload = function () {
   const table = document.getElementById('theTable');
   const widths = computeColumnWidths(table)
   setColumnWidths(table, widths)
}

function computeColumnWidths(table) {
  const widths = Array.from({ length: table.rows[0].cells.length })
                      .fill(0);
  
  for (let i = 0; i < table.rows.length; i++ ) {
    const row = table.rows[i]
    
    for (let j = 0; j < row.cells.length; j++) {
      const cell = row.cells[j]
      widths[j] = Math.max(widths[j], cell.offsetWidth);
    }
  }
  
  return widths;
}

function setColumnWidths(table, widths) {
  for (let i = 0; i < table.rows.length; i++ ) {
    const row = table.rows[i]
    
    for (let j = 0; j < row.cells.length; j++) {
      const cell = row.cells[j]
      cell.style.width = widths[j] + 'px';
    }
  }
}

function switchRow(ixRow){

  let table = document.getElementById('theTable');

  let row = table.rows[ixRow];
  let currentVisibility = row.style.display;

  row.style.display = currentVisibility == 'none' ? 'table-row' : 'none';

}

table{
  border: 2px solid black;
  padding: .5em;
}

<table id='theTable'>
<tr><td>Hellen</td><td>Smith</td></tr>
<tr><td>Montgomery</td><td>Wolfeschlegelsteinhausenbergerdorff</td></tr>
</table>
<br>
<button onclick="switchRow(1)">Switch row 1</button>