Find the number of <td>s in a <tr> without using id or name

How do you calculate the number of <td> elements in a particular <tr>?

I didn't specify id or name to access directly, we have to use the document.getElementsByTagName concept.

From stackoverflow

• You can use something like the following:

  var rowIndex = 0; // rowindex, in this case the first row of your table
  var table = document.getElementById('mytable'); // table to perform search on
  var row = table.getElementsByTagName('tr')[rowIndex];
  var cells = row.getElementsByTagName('td');
  var cellCount = cells.length;
  alert(cellCount); // will return the number of cells in the row
  

  Gene : you could add the check for "table" to support multiple tables.

  Aron Rotteveel : You're right, thanks.

• Something like

  var tot = 0;
  var trs = document.getElementsByTagName("tr");
  for (i = 0; i < trs.length; i++) {
      tds = trs[i].getElementsByTagName("td");
      tot += tds.length;
  }
  

  At the end, tot hold the total number of all td elements "sons" of tr elements.

• document.getElementsByTagName returns an array of elements, so you should be able to do something like this:

  var totals = new Array();
  
  var tbl = document.getElementById('yourTableId');
  var rows = tbl.getElementsByTagName('tr');
  for (var i = 0; i < rows.length; i++) {
      totals.push(rows[i].getElementsByTagName('td').length;
  }
  
  ...
  
  // total cells in row 1
  totals[0];
  // in row 2
  totals[1];
  // etc.
  

• var trs = document.getElementsByTagName('tr');
  for(var i=0;i<trs.length;i++){
    alert("Number of tds in row '+(i+1)+' is ' + tr[i].getElementsByTagName('td').length);
  }
  

  will alert the number of <td>s in each <tr> on the page.

• If you use the jQuery library, it should be as simple as this.

  $("table tr:eq(0) > td").length
  

  You can use anything as a selector as you would CSS3

  $("#mytableid tr").eq(0).children("td").length
  

  Would be another way to do it.

• tr.cells.length
  

  Is an easier way to spell it.

• bobince has the correct answer. I tried to give him some love, but I am new with a 0 rep.

  tr.cells.length is the quickest way to get what you want.

  Now, the assumption is that you already have a reference to the tr. If you don't, at some point you have to have a reference to the table. In the DOM, the table element has an array (actually an HTMLCollection) called rows.

  table.rows[r].cells[c]
  

  will give you the address of any cell where r = the index of the row and c = the index of the cell within that row.