PHP + Jquery Change Value of Textbox according to

问题:

I try to update text box value according to 2 dropdown. 1 drop down contain price1 and other drop down contain price 2, now I want that when user select price from both drop down then textbox display like that "price1 + price2 = total" How can I marge both value in single textbox value ? my price comes from database. Here is FIDDLE

PHP CODE

 <div class="three columns">
                    <div class="picker">
                        <select name="city" required>
                        <option value="" disabled>Select</option>
                            <?php 
                            $result = mysqli_query($con,"SELECT * FROM area");
                            while($row = mysqli_fetch_array($result))
                            {
                            ?>
                                <option value="New"><?php echo $row['city']."( $ ".$row['area'].")";; ?></option>
                            <?php } ?>
                        </select>
                    </div>
                </div>
                <div class="four columns">
                <div class="picker">
                    <select name="position" required>

                        <?php 
                            $result = mysqli_query($con,"SELECT * FROM pricing");
                            while($row = mysqli_fetch_array($result))
                        {
                        ?>
                            <option value="<?php echo $row['position']; ?>"><?php echo $row['position']."( $ ".$row['price'].")"; ?></option>
                        <?php } ?>
                    </select>
                </div>
            </div>
            <div class="row">
            <div class="two columns">
                Total
            </div>
            <div class="ten columns">
                <div class="field">
                  <input class="input" type="total" id="total" placeholder="" name="total" disabled/>
                </div>
            </div>

        </div>

回答1:

add a class on both combo and write one event this way:

$('.combo').change(function() {
    $('#firstvalue').val(parseInt($('#combo').val()) +parseInt($('#combo1').val()));
});

FIDDLE DEMO

or you can do this way:

$('.combo').change(function() {
    $('#firstvalue').val($('#combo').val() +"+"+$('#combo1').val()+"=");
    $('#firstvalue1').val(parseInt($('#combo').val()) +parseInt($('#combo1').val()));
});

SECOND DEMO

回答2:

use this..

$(document).ready(function() {

$('.combo').change(function() {
    $('#firstvalue').val(parseInt($('#combo').val()) +parseInt($('#combo1').val()));
});


$('#combo1').change(function() {
    $('#firstvalue1').val($('#combo1').val());
});
});

回答3:

you can do it by using variables:

if you wanted to sum of two dropdown options then you have to give integer value of the seond dropdown not the string(like a3,a4 should be 3,4). see demo html.

 $(document).ready(function() {
    price1=0;
    price2 =0;
    $('#combo').change(function() {
          price1= this.value;
          $('#firstvalue').val(parseInt(price1)+parseInt(price2));

    });


  $('#combo1').change(function() {
    price2 = this.value;
    $('#firstvalue').val(parseInt(price1)+parseInt(price2));
  });
});

demo