Limit checkboxes that can be checked

I am creating dynamic list on page. And the input element is propagated with data from db.

What I want to do is list the data, in input elements, with a checkbox at the end of each line. But I only want to be able to allow a user to click any 3 of the checkboxes.

Could be 20 options, but only 3 can be selected.

From here they can then proceed. So I have a submit button that I wish to disable unless 3 are clicked.

So the input elements and checkboxes are like so.

<input class="inputLONG" type="text" READONLY value="123 Hauton Road, Burpengary QLD 4506" class="small">&nbsp;&nbsp;<input name="approved" id="check1" value="1" type="checkBox" />
<input class="inputLONG" type="开发者_Python百科text" READONLY value="86 Clandestine Boulevard, Beachmere QLD 4505" class="small">&nbsp;&nbsp;<input name="approved" id="check2" value="1" type="checkBox" />
<input class="inputLONG" type="text" READONLY value="82 Sentinnel Court, Raby Bay QLD 4178" class="small">&nbsp;&nbsp;<input name="approved" id="check3" value="1" type="checkBox" />
<input class="inputLONG" type="text" READONLY value="1 Lido Court, Wellington Point QLD 4200" class="small">&nbsp;&nbsp;<input name="approved" id="check4" value="1" type="checkBox" />

And the Order Button. Which needs to be disabled unless three checkboxes are ticked.

<span class="samplePromo">Order</span>

Any help appreciated.

Oh and NO LESS than or NO MORE than 3 can be selected.

I have written a small snippet to do this for you in jsFiddle.

http://jsfiddle.net/mvelaga/Ed8jQ/

Edit:

New fiddle to address the scenario discussed in comments

http://jsfiddle.net/mvelaga/kKGcJ/1/

Found a script to do I think.

http://www.plus2net.com/javascript_tutorial/checkbox-limit.php

write custom function which will fire onclick (or onchange) of checkbox, disable rest of them when 3 are checked, enable buttom, react opposite if less than 3 are on...