Decide which object comes first in code

Quick JQuery-question: How can one decide which of two objects comes first in a code?

Edit: I want to do something like this.

var active = $("#second");
if(active is before $("#first")) ...
else ...

Ex:

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

<table>
<tr>
<td id="second"> </td>
<td>开发者_JAVA百科; </td>
<td> </td>
</tr>
</table>

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If you're using jQuery 1.4+, .add() will do the trick.

As of jQuery 1.4 the results from .add() will always be returned in document order (rather than a simple concatenation).

Reference: http://api.jquery.com/add/

You can write a simple plugin for this:

$.fn.isBefore = function (selector) {
    return this.add(selector)[0] == this[0];
};

Then use it like so:

if (active.isBefore("#first")) {...}
// "#first" can really be replaced with any valid expression that can be used
// by $().

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Use the first selector

$('table td:first');

See: http://api.jquery.com/first-selector/

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Have a look at :first

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try this...

$('table td').eq(0);