How to get a value of a selected row from html?

I want to get a selected row val开发者_开发百科ue of a table when we click on a row, how can i do this?

<script type="text/javascript">
window.onload=function() {
  var table = document.getElementById("table1");
  var tablerows = table.rows;
  for (var i=0, n=tablerows.length;i<n;i++) {
    tablerows[i].onclick=function() {
      alert(tablerows[i].textContent?tablerows[i].textContent:tablerows[i].innerText)
    }
  }
}
</script>