How do I iterate through table rows and cells in JavaScript?

Answer 1

var table=document.getElementById("mytab1");
var r=0; //start counting rows in table
while(row=table.rows[r++])
{
  var c=0; //start counting columns in row
  while(cell=row.cells[c++])
  {
    cell.innerHTML='[R'+r+'C'+c+']'; // do sth with cell
  }
}

<table id="mytab1">
  <tr>
    <td>A1</td><td>A2</td><td>A3</td>
  </tr>
  <tr>
    <td>B1</td><td>B2</td><td>B3</td>
  </tr>
  <tr>
    <td>C1</td><td>C2</td><td>C3</td>
  </tr>
</table>

In each pass through while loop r/c iterator increases and new row/cell object from collection is assigned to row/cell variables. When there's no more rows/cells in collection, false is assigned to row/cell variable and iteration through while loop stops (exits).

Answer 2

Using a single for loop:

var table = document.getElementById('tableID');  
var count = table.rows.length;  
for(var i=0; i<count; i++) {    
    console.log(table.rows[i]);    
}

Answer 3

This solution worked perfectly for me

var table = document.getElementById("myTable").rows;
var y;
for(i = 0; i < # of rows; i++)
{    for(j = 0; j < # of columns; j++)
     {
         y = table[i].cells;
         //do something with cells in a row
         y[j].innerHTML = "";
     }
}

Answer 4

You can use .querySelectorAll() to select all td elements, then loop over these with .forEach(). Their values can be retrieved with .innerHTML:

const cells = document.querySelectorAll('td');
cells.forEach(function(cell) {
  console.log(cell.innerHTML);
})

<table name="mytab" id="mytab1">
  <tr> 
    <td>col1 Val1</td>
    <td>col2 Val2</td>
  </tr>
  <tr>
    <td>col1 Val3</td>
    <td>col2 Val4</td>
  </tr>
</table>

If you want to only select columns from a specific row, you can make use of the pseudo-class :nth-child() to select a specific tr, optionally in conjunction with the child combinator (>) (which can be useful if you have a table within a table):

const cells = document.querySelectorAll('tr:nth-child(2) > td');
cells.forEach(function(cell) {
  console.log(cell.innerHTML);
})

<table name="mytab" id="mytab1">
  <tr> 
    <td>col1 Val1</td>
    <td>col2 Val2</td>
  </tr>
  <tr>
    <td>col1 Val3</td>
    <td>col2 Val4</td>
  </tr>
</table>

Answer 5

If you want to go through each row(<tr>), knowing/identifying the row(<tr>), and iterate through each column(<td>) of each row(<tr>), then this is the way to go.

var table = document.getElementById("mytab1");
for (var i = 0, row; row = table.rows[i]; i++) {
   //iterate through rows
   //rows would be accessed using the "row" variable assigned in the for loop
   for (var j = 0, col; col = row.cells[j]; j++) {
     //iterate through columns
     //columns would be accessed using the "col" variable assigned in the for loop
   }  
}

If you just want to go through the cells(<td>), ignoring which row you're on, then this is the way to go.

var table = document.getElementById("mytab1");
for (var i = 0, cell; cell = table.cells[i]; i++) {
     //iterate through cells
     //cells would be accessed using the "cell" variable assigned in the for loop
}

Answer 6

You can consider using jQuery. With jQuery it's super-easy and might look like this:

$('#mytab1 tr').each(function(){
    $(this).find('td').each(function(){
        //do your stuff, you can use $(this) to get current cell
    })
})