Question

HTML

<input name="pm" type="text" value="0"/>
<input name="pm" type="text" value="0"/>
<input name="pm" type="text" value="0"/>

<input name="total" type="text" value="0" disabled="disabled"/>

Javascript

$('[name="pm"]').keypress(function() {

//implementation ?

});

I have three text box by default value =0, as user write any one of the these three text box, total must be shown in total text box.
Key press event working fine for all three text boxes.

Answer 1

Simple demo http://jsfiddle.net/mZBtg/

Please note: I have used keyup api but it will give you same result what you are looking for.

http://api.jquery.com/keyup/

http://api.jquery.com/keypress/

You can also do isNumeric and isNan check; good link: $.isNumeric vs. isNaN Also please see comments below. B-)

Feel free to play around and hope this help.

code

$('input[name="pm"]').keyup(function() {
    var sum = 0;
    $('input[name="pm"]').each(function(){
        sum += parseInt(this.value);
    });
   $('input[name="total"]').val(sum);
});​