How to find the index of a row in a table using jquery

Based on Robs answer to find index in specific table, this worked for me.

var index = $('tr', $(this).closest("table")).index(this);

I've just found an interesting trick, which basically consists on counting the previous siblings:

var tr = $(some_selector);
var rowIndex = tr.prevAll().length;

This way you will get 0 if this is the first tr, 3 if this is the 4th tr, etc.

Just for the sake of it, another option using index(), which saves you from having to know how to select the containing table:

var rowIndex = tr.parent().children().index(tr);

Try:

var index = $("table tr").index(this);

The documentation for index() says:

Searches every matched element for the object and returns the index of the element, if found, starting with zero. If a jQuery object is passed, only the first element is checked.

You need to call the index() on a collection of <tr> elements, not the parent <table>.

Have you tried:

$("tr").index(this)

The documentation shows just passing this and that the preceding selection should be where the node is found. If you need to find it in a specific table (and there are multiple), you may need to provide some context:

// haven't tested this
$("tr", $(this).closest("table")).index(this)