如何使用javascript向已有的html表添加新列

var table = document.getElementById("myTable");

var th = document.createElement("th");
th.innerHTML = "New Column";

var headerRow = table.rows[0];
headerRow.appendChild(th);

for (var i = 1; i < table.rows.length; i++) {
  var cell = table.rows[i].insertCell();
  cell.innerHTML = "New Cell";
}

var table = document.getElementById("myTable");
var th = document.createElement("th");
th.innerHTML = "New Column";
var headerRow = table.rows[0];
headerRow.appendChild(th);

for (var i = 1; i < table.rows.length; i++) {
  var cell = table.rows[i].insertCell();
  cell.innerHTML = "New Cell";
}