Adding rows and columns to an HTML table

Let's say we have some HTML table - #table. Let's learn how to add new rows and columns to it.

Adding rows

Adding rows is not difficult: you need to create tr, and then run a loop that will add the desired number of cells to this row (let's say 3):

let table = document.querySelector('#table');

let tr = document.createElement('tr');

for (let i = 1; i <= 3; i++) {
	let td = document.createElement('td');
	tr.appendChild(td);
}

table.appendChild(tr);

Make a button, by clicking on which a new row will be added to the table.

Adding columns

But with adding columns, it’s a little more complicated: you need to run a loop that will go through all the table rows and add a new cell to each row:

let trs = document.querySelectorAll('#table tr');

for (let tr of trs) {
	let td = document.createElement('td');
	tr.appendChild(td);
}

Given a 2 by 2 table:

<table id="table">
	<tr>
		<td></td>
		<td></td>
	</tr>
	<tr>
		<td></td>
		<td></td>
	</tr>
</table>

td {
	width: 50px;
	height: 50px;
	border: 1px solid black;
}

There is also a button. Make it so that when you click on the button, the table increases by one row and one column.