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How can I get a clicked table row's TBODY?

I have a table with a few rows in it. Each row has an onclick event that is supposed to check the ID of the tbody element. This is stored in a variable for later use in a function.
Right now I have this snippet of jQuery:
var parentTable = $(this.parentNode)[0].id;
However, this only gets the ID of the entire table, not the tbody.
What's the best way to specify the ID of the tbody element?

First, your use of jQuery is wasted there. It would be written like this:
var parentTable = this.parentNode.id;
As far as getting the tbody id, assuming this is actually the row, your code should do it.
If you're actually getting the table, then that would be very unusual. The only way a tbody would not get created would be if you manually created the table from DOM creation methods, and left it out.

You may want to store that information in a data-tbody-id for each row, then when the user clicks on the row, the event object will hold that information.

You can use the following function
var tobody = parentTable.children('tbody')

You can use the following function
var tbody = $(this).parents("tbody");
var id = tbody.attr("id");

jQuery remove tr with no results

I have a SQL-PHP printed table, and a select at the top of the table. The table contains contacts classified by towns.
At the beginning, the table shows all contacts. If I specify the town, I want to hide the rest.
I'm trying to use a jQuery script
<script>
function updateit(){
if ($("#table").filter("tr") === $("#selectTown").val()) $(this).show(););
else {$(this).hide();};
}
</script>
[...]
<select id="selectTown" onchange="updateit()"><option value="NY">New York</option><option value="TX">Texas</option></select>
<table id="table">
bla bla bla...
</table>
Before I tried with find() function, but with no success.
Any suggestions?

This line $("#table").filter("tr") === $("#selectTown").val() compares document elements to string, it would not work.
Simplest solution would be to do all elements hidden and than select and show all matching elements. Example:
$('tr').hide();
$('tr[value=' + $("#selectTown").val() + ']').show();

I'm not sure where you got the idea for this code, but filter() definitely doesn't do what you think it's doing. $("#table").filter("tr") is going to give you a list of tr elements in the table. That list itself isn't going to equal any selected value, it's just an array of elements.
Mocking up a few things in a jsFiddle here, perhaps you want something more like this:
$('#selectTown').change(function () {
$('#table tr').hide();
$('#table tr').filter(function () {
return $(this).find('td:first').text() === $('#selectTown').val();
}).show();
});
What this does is:
Bind to the change event of the select element (which is preferred over the inline binding you do in your markup, just in general).
Hide all of the tr elements first, you'll show the ones you want in a moment.
Show all of the tr elements which match the filter.
The filter in this case is a function which returns true if the text inside of the td element (you will likely need to update that selector) equals the selected value. The main difference here vs. what you tried is that .filter() is returning a list of matched (filtered) elements, not an actual value to compare. Internal to the filter is where the comparison takes place, in this case using a function (which needs to return true or false for any given element being filtered).

How to compare if two elements are the same?

I am trying to compare if the two td elements are the same within 1 table.
I have
var element = $('.table td');
$('table:odd td','.table').each(function(){
if(element.is(this)){
console.log('find')
}
)}
I want to check if the element is the same as this but my codes don't seem to work here.
Can anyone give me a hint for it? Thanks a lot

regular DOM nodes can be compared against each other, and using get(0) will get you the first DOM node from the jQuery collection :
var element = $('.table td');
$('table:odd td','.table').each(function(){
if (element.get(0) === this ){
console.log('find');
}
});
It does look like element would contain more than one element, especially as you're iterating the same selector with an added :odd on the next line, so the comparison seems a little strange, and will probably return false ?

Change text of specific <a> text using jQuery

I have an asp:Repeater that makes a table with a few <td>s and <tr>s. In each of the <tr>s, I have an <a></a>.
Now, on a certain event I want to change just the <a></a> tag in the <tr>.
So, I want to do something like:
$("a").text("I changed!");
, but I only want to change the <a>.text in one <tr>, not all the <a> elements on the page.
I am experimenting with .closest(), but unfortunately don't know enough about jQuery to make this functional.

if you have the target tr somehow, then you can use the following code to find the a tag inside that:
tr.find("a").text("text here");
How to find tr really depends on what context you are in and how your target tr is identified from others.
e.g. if it's the "first" tr you may say:
var tr = $("tr").first();
if it's the element that the event has happened for (e.g. click event):
var tr = $(this);
if you are in the event of a child element of target tr you may say:
var tr = $(this).closest("tr");

You should mark the <tr> with an Id so that you could identify it and then change the containing
So for example you could mark your <tr> with id 'myid' and do something like this in jquery:
$("#myid a").text("I changed!");
Or if you dont want to mark it with an Id then, you could use selectors if you know which it is.
For example getting the first would be:
$("tr:first a").text("I changed!");
Some references:
http://api.jquery.com/first-selector/
http://api.jquery.com/category/selectors/

remove parent container

I have a form with the fields inside table cells. On the last column of each line I have an image. When clicking that image I want to delete the parent <tr>. Before I tried to do it by generating a function passing as the argument the line number: onclick='delete_row(x, y)'. This is obviously not a good solution since I was deleting the row by its position. The function I'm calling has other 2 arguments since it deletes the row in the database too, so the second argument is the id in the database to delete. So basically I need a function that deletes the parent <tr> and that accept some other arguments too.
EDIT Thanks:
Thank you all guys, I tried almost all the solutions and all worked nice. I just decided for the Mike's Samuel one, it seemed the easiest :) Thanks again

To pass the grandparent of the current node use this.parentNode.parentNode:
<tr><td><img onclick="delete_row(this.parentNode.parentNode, ...)"></td></tr>

How about removing the closest <tr>? You would need to make accommodations for the selectors that are present in your code, but the general form looks like this:
$('img').click(function(){
$(this).closest('tr').remove();
});

You could easily use the HTML node method .removeChild() and traverse through the node's .parentNodes: (demo):
<td onclick="this.parentNode.parentNode.removeChild(this.parentNode);">
Remove row
</td>
this.parentNode.parentNode will be the <table> or <tbody>, while this.parentNode is the parent container <tr>.
Update: rjz provided a neat function (demonstration):
window.removeClosestRow = function(node) {
while(node = node.parentNode) {
if (node.tagName.toUpperCase() == 'TR') {
node.parentNode.removeChild(node);
break;
}
}
}

try something like
onClick='MyDeleteFunc(this, var2, var3)';
that will pass the actual object you're clicking on to javascript, and you can get pretty much all your references from there.