​x
 
<!DOCTYPE html>
<html>
<head>
<script>
function getCellContent(id) {
  var x = document.getElementById(id).rows[0].cells;
  document.getElementById("demo").innerHTML = x[0].innerHTML;
}
</script>
</head>
<body>
​
<table id="myTable" style="border: 1px solid black">
  <tr>
    <td>cell 1</td>
    <td>cell 2</td>
  </tr>
  <tr>
    <td>cell 3</td>
    <td>cell 4</td>
  </tr>
</table>
​
<p>
<input type="button" onclick="getCellContent('myTable')" value="显示第一个单元格">
</p>
​
<p id="demo"></p>
​
</body>
</html>
​