Develop Reference

Using a variable to select a row from a html table

I'd like to use this code to select a particular row
var table = document.getElementById("mytable");
table.rows[0].cells[3].innerHTML = 'here';
and instead of entering the row number I want to put a variable holding a number inside so I can locate a specific row.
The number of rows on the table can change.
Is there any other way to do this?

var table = document.getElementById("mytable");
table.rows[0].cells[3].innerHTML = 'here';
<table id="mytable" border="2">
<tr>
<td>25</td>
<td>25</td>
<td>25</td>
<td>25</td>
</tr>
</table>

How to clone a whole table in Javascript?

I tried to use cloneNode mentionned here Copy the content of one table into another but Chrome says cloneNode is not a function
https://jsfiddle.net/4wczdykc/1/
<table>
<thead>
<tr>
<th scope="col" colspan="1">TABLE TO CLONE</th>
</tr>
<tr>
<th>Column</th>
</tr>
</thead>
<tbody>
<tr>
<td></td>
</tr>
</tbody>
</table>
script:
myTable = document.getElementsByTagName("Table")[0];
myClone = myTable.cloneNode(true);
document.body.appendChild(myClone);

The getElementsByTagName() method accesses all elements with the specified tagname.So you have to select the first element of the NodeList. So passed [0] to select it.
myTable = document.getElementsByTagName("table")[0];
myClone = myTable.cloneNode(true);
document.body.appendChild(myClone);
WORKING FIDDLE

get the content of one column of each row in the table and then loop on each content

I have a table structure like this (refer below)
<table>
<thead>
<tr><th>id</th><th>name</th><th>address</th></tr>
</thead>
<tbody>
<tr rowid="1">
<td class="columnid">1</td><td class="columnname">name 1</td><td class="columnaddress">address 1</td>
</tr>
<tr rowid="2">
<td class="columnid">2</td><td class="columnname">name 2</td><td class="columnaddress">address 2</td>
</tr>
<tr rowid="3">
<td class="columnid">3</td><td class="columnname">name 3</td><td class="columnaddress">address 3</td>
</tr>
</tbody>
</table>
Now, I want to get the content from each table row that has attr('columnid') and loop each of it. So the code structure would look like this (refer below)
//We have 3 row, get all present rowid (1,2,3)
//count all the row that has rowid attribute
var rowcount = attr('rowid').length();
var i;
for (i = 0; i < rowcount; i++) //I dont know how to make it but assume in this for statement, I have stored the content from each rowid attribute {
//alert each rowid here
}
how to make it? any help, suggestions, recommendations, ideas, clues would be greatly appreciated. Thank you.

You can use tr[rowid] which will find all tr elements with rowid attribute, then use .has() to filter out trs which do not have td with class columnid like
$('tr[rowid]').has('td.columnid').each(function(){
alert($(this).attr('rowid'))
});
Demo: Fiddle

This code will scan all the td's with class columnidand alert the rowid of the row containing it. I hope this is what you want you code to do.
$("tr td.columnid").each(function(){
alert($(this).parent().attr("rowid"));
});
Fiddle

jQuery: skipping first table row

This is the HTML:
<table id="tblTestAttributes">
<thead>
<tr> <th>Head 1</th> <th>Head 2</th> </tr>
</thead>
<tbody>
<tr> <td id="txtDesc">Item 1</td> <td id="ddlFreq">Assume a DropDownList Here</td> </tr>
<tr> <td id="txtDesc">Item 1</td> <td id="ddlFreq">Assume a DropDownList Here</td> </tr>
<tr> <td id="txtDesc">Item 1</td> <td id="ddlFreq">Assume a DropDownList Here</td> </tr>
</tbody>
</table>
This is the javascript to get the values of each row:
var frequencies = [];
if ($('#tblTestAttributes').length) {
$('#tblTestAttributes tr').each(function () {
var t = $(this).find('td[id^="txtDesc"]').text() + ";" + $(this).find('[id^="ddlFreq"] option:selected').val();
alert(t);
frequencies.push(t);
});
}
I want to avoid the first row, which contains th elements which are just display headers and don't contain any data.
So I changed the selector to this:
#tblTestAttributes tr:not(:first-child)
This is skipping the second tr as well. What is happening here?

Simple you can use below code
$('#tblTestAttributes tr:not(:has(th))').each(function () {

In terms of performance, using .find() will be better than resolving the selector with Sizzle.
$('#tblTestAttributes').find('tbody').find('tr').each(function () { ... });
Here's the jsPerf to show it.

use
#tblTestAttributes tr:gt(0)
or
#tblTestAttributes tbody tr
I would recommend the 2nd, because it may take advantage of querySelectorAll and should be the fastes solution.
your approach didn't work as expected, because the 2nd tr is also a first-child(of tbody)

Use tr + tr selector, which gets all tr that appear after another tr, so the first one is skipped.
Also no need to check if table exists, as in that case $.each wouldn't even get executed.
var frequencies = [];
$('#tblTestAttributes tr + tr').each(function () {
var t = $(this).find('td[id^="txtDesc"]').text() + ";" + $(this).find('[id^="ddlFreq"] option:selected').val();
alert(t);
frequencies.push(t);
});
After your edit:
Simply select only all tr inside tbody:
$('#tblTestAttributes tbody tr').each(function(){
...
}

It happens because the second row is, in fact, the first child of the tbody just like the first row is the first child of the thead.
To only take the elements you need, I'd suggest something nearer from your need :
#tblTestAttributes tr:has(td)
Don't forget to get rid of those duplicate txtDesc id, this is illegal in HTML, use a class instead.

an easy way to get all the table rows from a table without using a loop

Is there an easy way to get all the table rows from a table without using a loop.
I thought that this would work but it only alerts the first row.
http://jsfiddle.net/THPWy/
$(document).ready(function () {
var O = $('#mainTable').find('tr');
//var O = $('#mainTable tr');
alert(O.html());
//alerts <th>Month</th><th>Savings</th>
});
<table id ="mainTable" border="1">
<caption>Monthly savings</caption>
<tr>
<th>Month</th>
<th>Savings</th>
</tr>
<tr>
<td>January</td>
<td>$100</td>
</tr>
<tr>
<td>February</td>
<td>$50</td>
</tr>
<tr>
<td>March</td>
<td>$50</td>
</tr>
<tr>
<td>a</td>
<td>$50</td>
</tr>
<tr>
<td>m</td>
<td>$50</td>
</tr>
<tr>
<td>j</td>
<td>$50</td>
</tr>
<tr>
<td>july</td>
<td>$50</td>
</tr>
<tr>
<td>aug</td>
<td>$50</td>
</tr>
<tr>
<td>sep</td>
<td>$50</td>
</tr>
</table>

Whatever you use will be iterating through each row to get the inner HTML out of it. So no, you cannot do it without a loop.
Here is an alternate method that gets the message in one line if that's what you're after, it's slightly less efficient than going with a loop though as it needs to make a new array.
jsFiddle
$(document).ready(function () {
var rows = $('#mainTable tr');
var message = $.map(rows, function (v) {
return v.innerHTML;
}).join('\n');
alert(message);
});
I would recommend just doing it in a regular loop.
FYI .html() only alerts the first row because that's what it was designed to do as that is what would be most useful.
Description: Get the HTML contents of the first element in the set of matched elements.

What about:
// get all tr (excluding the caption)
var O = $('table#mainTable').children().slice(1);
http://jsfiddle.net/THPWy/7/

What you have in your code already retrieves all table rows as an array of jQuery elements:
var trs = $('#mainTable').find('tr');
If you want to print the html contents of each row then you would have to use a loop:
trs.each(function (index, element) {
alert($(this).html());
});

You can get by using
gt(), lt(),eq()
.gt(index) // will get all the rows greater than specified index
.lt(index) // will get all the rows less than specified index
.eq(index) // will get all the rows equal to specified index
For Example
$('#mainTable tr').eq(1) will give second row
But when you want to know all the table rows data then go with Konstantin D - Infragistics solution