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

If I have an HTML table...say

<div id="myTabDiv">
<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>
</div>

How would I iterate through all table rows (assuming the number of rows could change each time I check) and retrieve values from each cell in each row from within JavaScript?

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
}

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
    })
})

Try

for (let row of mytab1.rows) 
{
    for(let cell of row.cells) 
    {
       let val = cell.innerText; // your code below
    }
}

for (let row of mytab1.rows) 
{
    for(let cell of row.cells) 
    {
       console.log(cell.innerText)
    }
}

<div id="myTabDiv">
<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>
</div>

for ( let [i,row] of [...mytab1.rows].entries() ) 
{
    for( let [j,cell] of [...row.cells].entries() ) 
    {
       console.log(`[${i},${j}] = ${cell.innerText}`)
    }
}

<div id="myTabDiv">
<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>
</div>

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).

Better solution: use Javascript's native Array.from() and to convert HTMLCollection object to an array, after which you can use standard array functions.

var t = document.getElementById('mytab1');
if(t) {
    Array.from(t.rows).forEach((tr, row_ind) => {
        Array.from(tr.cells).forEach((cell, col_ind) => {
            console.log('Value at row/col [' + row_ind + ',' + col_ind + '] = ' + cell.textContent);
        });
    });
}

You could also reference tr.rowIndex and cell.colIndex instead of using row_ind and col_ind.

I much prefer this approach over the top 2 highest-voted answers because it does not clutter your code with global variables i, j, row and col, and therefore it delivers clean, modular code that will not have any side effects (or raise lint / compiler warnings)... without other libraries (e.g. jquery).

If you require this to run in an old version (pre-ES2015) of Javascript, Array.from can be polyfilled.

If you want one with a functional style, like this:

    const table = document.getElementById("mytab1");
    const cells = table.rows.toArray()
                  .flatMap(row => row.cells.toArray())
                  .map(cell => cell.innerHTML); //["col1 Val1", "col2 Val2", "col1 Val3", "col2 Val4"]

You may modify the prototype object of HTMLCollection (allowing to use in a way that resembles extension methods in C#) and embed into it a function that converts collection into array, allowing to use higher order funcions with the above style (kind of linq style in C#):

    Object.defineProperty(HTMLCollection.prototype, "toArray", {
        value: function toArray() {
            return Array.prototype.slice.call(this, 0);
        },
        writable: true,
        configurable: true
    });

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 = "";
     }
}

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>

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]);    
}

My solution, using es6:

var table = document.getElementById('mytab1');

var data = [...table.rows].map(row => [...row.cells].map(td => td.innerText));

console.log(data)

REFERENCES:
https://developer.mozilla.org/pt-BR/docs/Web/API/HTMLCollection

Here's one solution using modern Javascript ES6+

    const rows = document.querySelector("table")?.rows;
    if (!rows) {
      return;
    }
    Array.from(rows).forEach(row => {
      console.log(row);
      const cells = Array.from(row.cells);
      cells.forEach(cell => {
        console.log(cell);
      });
    });

Array.from() converts the HTMLCollection of rows and/or cells into a regular Javascript Array which you can iterate through.

Documentation for table.rows usage: https://developer.mozilla.org/en-US/docs/Web/API/HTMLTableElement/rows

Documentation for row.cells usage: https://developer.mozilla.org/en-US/docs/Web/API/HTMLTableRowElement

I leave this just for future reference for scraping a specific HTML table column and printing the results.

//select what table you want to scrape (is zero based)
//set 0 if there is only one
setTable=0;
//select what column you want to scrape (is zero based)
//in this case I would be scrapping column 2
setColumnToScrape=1;
var table = document.getElementsByTagName("tbody")[setTable];
for (var i = 0, row; row = table.rows[i]; i++) {
  col = row.cells[setColumnToScrape];
  document.write(col.innerHTML + "<br>");
}

This is a different method using the childNodes and HTMLCollection

    <script>
        var tab = document.getElementsByTagName("table")
        for (var val of tab[0].childNodes[1].childNodes.values())
            if (HTMLCollection.prototype.isPrototypeOf(val.children)) {
                for (var i of val.children) {
                    console.log(i.childNodes[0])
                }
            }
    </script>

Pure Javascript

function numberofRow(){
  var x = document.getElementById("mytab1").rows.length;
  document.getElementById("mytab1").innerHTML = x;
}
numberofRow();

<div id="myTabDiv">
<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>
</div>

es6:

const table = document.getElementById('some-table');
const cells = table.getElementsByTagName('td');

for (let cell of cells) {
   // do something with cell here
}

earlier versions:

var table = document.getElementById('some-table');
var cells = table.getElementsByTagName('td');
for ( var i in cells ) {
   // do something with cells[i]
}

source: https://developer.mozilla.org/en-US/docs/Web/API/Element/getElementsByTagName