how do i calculate 2 input fields and put results in 3rd input field

Question

i want to have a form whereby i can add a value into the first text field, multiply that by a second hidden field, and display results in a 3rd text field. I want it so as soon as you add a value to the first field it shows the result in the 3rd field, eg on key up.

<label>Qty:</label>
<input name="qty" id="qty" type="text" />
<input name="price" id="price" type="hidden" value="30" /><br />

<label>Total:</label>
<input name="total" id="total" type="text" />

Any help would be great as im new to jquery.

Have a read in the [jQuery API](http://api.jquery.com) about the `keypress` handler, as well as the `val()` function. Other than that, its basic maths. — Rory McCrossan, Aug 18 '13 at 14:41

score 4 · Answer 1 · answered Aug 18 '13 at 14:46

4

$("#qty").keyup(function(){
   total = $("#qty").val()* $("#price").val();
   $("#total").val(total);
});

answered Aug 18 '13 at 14:46

Akhil5

210
2
8

and thanks to Akhil5, your solution worked too. so easy when you know how :) – user2489811 Aug 18 '13 at 14:51
Please try to explain why your solution works as well as giving the code. – Sled Aug 18 '13 at 15:04

score 4 · Accepted Answer · answered Aug 18 '13 at 15:10

Though you got the answer but you should type cast the values you type in inputs. I mean what if someone type any other value other than integer... then you will get NaN in 3rd textbox..Here is solution to handle this problem

$(document).ready(function(){
    var qty=$("#qty");
    qty.keyup(function(){
        var total=isNaN(parseInt(qty.val()* $("#price").val())) ? 0 :(qty.val()* $("#price").val())
        $("#total").val(total);
    });
});

or you can check jsfiddle http://jsfiddle.net/ugPxf/

Can you help me to make this calculator? http://services.resellerbytes.com/business-email — shaz3e, Sep 03 '17 at 18:24

score 0 · Answer 3 · answered Aug 18 '13 at 14:45

0

This should work.

$('#qty').on('keyup',function(){
     $('#total').val( $('#qty').val() * $('#price').val());
});

R.

answered Aug 18 '13 at 14:45

Rob Schmuecker

8,934
2
18
34

how do i calculate 2 input fields and put results in 3rd input field

3 Answers3

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