Tryit Editor v1.8

Source Code:
<!DOCTYPE html> <html> <head> <script> function cell() { var x=document.getElementById('myTable').rows[0].cells; alert(x[0].innerHTML); } </script> </head> <body> <table id="myTable" border="1"> <tr> <td>cell 1</td> <td>cell 2</td> </tr> <tr> <td>cell 3</td> <td>cell 4</td> </tr> </table> <br> <input type="button" onclick="cell()" value="Alert first cell"> </body> </html>
Result:
W3Schools.com - Try it yourself