Getting total length of an index in each()

I want to get an unknown (changing) # of rows from a table, between the 1st cell and the last 3. I'm using jQuery's each and don't know why $(this).length doesn't give the total length of the index.

jQuery:

$("#parent table:first tr").each(function(i){
    var  goodlng =  $(this).parent().children("tr").length -1;   //this works
    var badlng = $(this).length -1;                        //this doesn't! (always == -1)
});

Is the goodlng good practice? it seems like a hack to have to go to parent and then back to children. Here is a jsfiddle开发者_运维问答 (have console.log()) open.

Example HTML:

<div id="parent">
    <table>
        <tr>
            <td>unwanted 1</td>
        </tr>
        <tr>
            <td>wanted!</td>
        </tr>
        <tr>
            <td>unwanted2</td>
        </tr>
    </table>
</div>

tl;dr: Why doesn't $(this).length == $(this).parent().children("tr").length inside of an each function. and is there another better way of doing this.

---

Your question says "cells", but it seems like you're trying to get the number of rows.

If you really want it inside the .each(), you could use the siblings()^[docs] method and the andSelf()^[docs] method.

$(this).siblings().andSelf().length

But if the rows aren't changing, why do it repetitively?

Or if they are changing, I'd just use the native rows property on the table to get the length.

var table = $("#parent table:first");

table.find('tr').each(function() {

    var len = table[0].rows.length;

});

---

Actually, this $(this).parent().children("tr").length is the correct way of handling things. this, in the context above is a reference to the tr node itself. tr.length = the length of the tr. tr.parent().children("tr"), on the other hand is a list of the node's siblings, so tr.parent().children("tr").length is the number of siblings.

---

This is the context of EACH element, not all of them. Therefore, this is only ONE tr at a time. That is why the length does not have all the elements.

---

The each() function is unaware of the collection of elements that it is working on. It is dealing with a single element at all times. Thats why when you go to the parent and ask for all children you get the right answer.

  $(this)

simply refers to the current tr element that you are dealing with, not a collection of them.