query add two input fields together

Question

I have the following code. I want to add two input fields together and output it to the page. I get as far as being able to output what is type in the input field however I can't figure how to add the two fields together and output it. I have it at http://jsfiddle.net/erick/9Dj3j/3/

Jquery

$(function() {
    var output_element = $('#output_ele');
    var output_element1 = $('#output_ele1');

    $('#the_input_id').keyup(function() {  
        var their_input = $(this).val();
        var firstInput = output_element.text(their_input);


    });
     $('#the_input_id1').keyup(function() {  
        var their_input1 = $(this).val();
        var firstInput1 = output_element1.text(their_input1);


    });

    var output_total = $('#total');

    var total = firstInput + firstInput1;

   output_total.text(total);

 });

HTML

<form method="post">
    <input type="text" id="the_input_id">
    <input type="text" id="the_input_id1">
</form>
<div id="output_ele">

</div>
<div id="output_ele1">

</div>
​<div id="total">

</div>​​​​​​​​​​​​​​​

Answer 1

The code you posted isn't working for a couple of reasons

• On keyUp you assign the new values to firstInput and firstInput1 which are local to the callback
• The total value is calculated outside these callbacks and hence doesn't have access to those locals (the values are almost certainly undefined)
• The total is only calculated once on startup instead of once per click

What you need to do is write a function that adds the two values together and call that from the keyUp handler

$('#the_input_id').keyup(function() {  
    updateTotal();
});

$('#the_input_id1').keyup(function() {  
    updateTotal();
});

var updateTotal = function () {
  var input1 = parseInt($('#the_input_id').val());
  var input2 = parseInt($('#the_input_id1').val());
  if (isNaN(input1) || isNaN(input2)) {
    $('#total').text('Both inputs must be numbers');
  } else {          
    $('#total').text(input1 + input2);
  }
};

Fiddle: http://jsfiddle.net/9Dj3j/56/

Answer 2

I did a little modification on the answer above and here is the final javascript:

$(function() {

$('#the_input_id, #the_input_id1').keyup(function(){
   updateTotal(); 
});

var updateTotal = function () {
  var input1 = parseInt($('#the_input_id').val());
  var input2 = parseInt($('#the_input_id1').val());
  if (isNaN(input1) || isNaN(input2)) {
      if(!input2){
          $('#total').val($('#the_input_id').val());
      }

      if(!input1){
            $('#total').val($('#the_input_id1').val());
      }

  } else {          
        $('#total').val(input1 + input2);
  }
};

var output_total = $('#total');

var total = input1 + input2;

output_total.val(total);

});

Fiddle: http://jsfiddle.net/9Dj3j/259/