passing value returned from javascript to php

Question

hi I am really novice in programming and doing some PHP development to support a personal commitment.

I have written a javascript to do some calculations and return the answer. I want to access this value from my php and print it.

following are the code components.

<?php include 'dbconnection.php'; ?>
<?php

  $Kg=0.00;
 $Rate=0.00;  $MinusBags=0.00; $Amount = 0.00;
 $KgIntoRate=0.00;
//$Amount = $KgIntoRate - $MinusBags;



//execute the SQL query and return records
$result = mysql_query("SELECT EmployeeName FROM employees");
$result2 = mysql_query("SELECT SRate FROM scraprates where SYear=YEAR(CURRENT_DATE()) AND SMonth=MONTHNAME(CURRENT_DATE())");
$temp1 = mysql_fetch_array($result2);
$Rate = $temp1['SRate'];
//$Rate=mysql_fetch_array($result2);


//fetch the data from the database 
try{
while ($row = mysql_fetch_array($result)) {
    echo "<tr><td>".$row{'EmployeeName'}."</td>";
    echo "<td><input type='text' name='Kg' id='Kg' onChange='CalcKgIntoRate();'/></td>";
    echo "<td>".$Rate."</td>";


//  $KgIntoRate = $_GET['php_KgIntoRate'];
    //echo "<td>".$_GET['php_KgIntoRate']."</td>";
    echo "<td>".$KgIntoRate."</td>";

    echo "<td><input type='text' name='MinusBags'/></td>";
    echo "<td>".$Amount."</td></tr>";
}
}
catch(Exception $e)
{echo "error".$e;}
?>

<script type="text/javascript">
//$Kg= $('#Kg').val();
function CalcKgIntoRate(){
var Kg=document.getElementById('Kg').value;
var php_rate = "<?php echo $Rate; ?>";
var php_KgIntoRate = "<?php echo $KgIntoRate; ?>";
//document.write(Kg);
php_KgIntoRate=Kg*php_rate;
return php_KgIntoRate;
}
</script>

<?php
//function CalcKgIntoRate(){
//$KgIntoRate = $Kg * $Rate;
//echo "<td>".$KgIntoRate."</td>";
//}


//close the connection
mysql_close($dbhandle);
?>

what i want to do is this. Names and Rate are coming from two database tables. I want to calculate KgIntoRate based on the Kg's entered (on change event of text field) and show the value in the Kg * Rate field.

I read that I need to use Ajax. but don't know how to do it. Appreciate some help with the code.

Please, don't use mysql_* functions in new code. They are no longer maintained and are officially deprecated. See the red box? Learn about prepared statements instead, and use PDO or MySQLi - this article will help you decide which. If you choose PDO, here is a good tutorial. — h2ooooooo
– h2ooooooo, Commented Jun 27, 2013 at 8:32
Do you want to stay on the same PHP page ? I mean do you mind if we get the values to the php variable in the next page where the JAVASCRIPT will post ? — Ashrith Sheshan
– Ashrith Sheshan, Commented Jun 27, 2013 at 8:33
if you want to stay on the same page we have to use AJAX ... other wise we can just create a form using JAVASCRIPT and post it to another PHP page where we can happily accept it into php Variable — Ashrith Sheshan
– Ashrith Sheshan, Commented Jun 27, 2013 at 8:34
Why don't you do the calculation in PHP? Or why you don't print the value in JS? — Carlos Campderrós
– Carlos Campderrós, Commented Jun 27, 2013 at 8:41
i need to stay on the same page.. let me explain a bit more. I am generating a table in php with the following columns. 1. Employee Name --> pulled from database table called 'employees' 2. Kg --> a text field to input the amount of Kg's 3. Rate for the month --> pulled from database table called 'scraprates' 4. Kg * Rate --> Here I want to multiply the Kg amount entered by the user with the rate and display in the column (there is no text box for this). I want this calculation to happen for the Onchange event of the Kg text box — user2527186
– user2527186, Commented Jun 27, 2013 at 10:24

Artur Gonçalves · Accepted Answer · 2013-06-27 09:13:05Z

1

I think in your example what your missing is just passing the value back to the Input field.

   function CalcKgIntoRate(){
var Kg=document.getElementById('Kg').value;
var php_rate = "<?php echo $Rate; ?>";
var php_KgIntoRate = "<?php echo $KgIntoRate; ?>";
//document.write(Kg);
php_KgIntoRate=Kg*php_rate;
//return php_KgIntoRate;

// here! instead of returning the value, set it as the value of your Input
document.getElementById('Kg').value = php_KgIntoRate;}

or you could simply make the calculations in php....

$result1 = $Rate * $KgIntoRate;
echo "<tr><td>".$row{'EmployeeName'}."</td>";
echo "<td><input type='text' name='Kg' id='Kg' value='".$result1."'/></td>";
echo "<td>".$Rate."</td>";

edited Jun 27, 2013 at 9:13

answered Jun 27, 2013 at 8:59

Artur Gonçalves

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4 Comments

user2527186 Over a year ago

let me explain a bit more. I am generating a table in php with the following columns. 1. Employee Name --> pulled from database table called 'employees' 2. Kg --> a text field to input the amount of Kg's 3. Rate for the month --> pulled from database table called 'scraprates' 4. Kg * Rate --> Here I want to multiply the Kg amount entered by the user with the rate and display in the column (there is no text box for this). I want this calculation to happen for the Onchange event of the Kg text box

Artur Gonçalves Over a year ago

haaa ok now i understand so you need to update the rate column, assign an Id to that column and then update its innerHTMl echo "<td id="rateColumn">".$Rate."</td>"; in the js funtion add this document.getElementById('rateColumn').innerHTML= php_KgIntoRate;

Artur Gonçalves Over a year ago

if you need to update any Db values then you would need some ajax...or submit a FORM

user2527186 Over a year ago

hmm.. i may need to save this table at the end.. I will think about that when i get to that point :-)

skparwal · Accepted Answer · 2013-06-27 11:21:36Z

1

You can do it wihtout ajax if your calculation is handled in javascript:

Check if it helps you.

e.g. Changes are in PHP code:

$i = 0; // define outside the loop

echo "<td><input type='text' name='Kg' id='Kg".$i."' onChange='CalcKgIntoRate(".$i.");'/></td>";
echo "<td id='rate".$i."'>".$KgIntoRate."</td>";
echo "<td id='kg_into_rate".$i."'>".$Amount."</td></tr>";
$i++;

JS Code:

function CalcKgIntoRate(i) {
    var kg = document.getElementById('Kg'+i).value;
    var rate = document.getElementById('rate'+i).innerHTML;
    var kg_into_rate = document.getElementById('kg_into_rate'+i);

    // here is your calculation login
    // suppose you store the calculation in an another variable
    var calVal = parseFloat(kg*eval(rate));
    kg_into_rate.innerHTML = calVal;
}

edited Jun 27, 2013 at 11:21

answered Jun 27, 2013 at 8:43

skparwal

1,0746 silver badges15 bronze badges

2 Comments

user2527186 Over a year ago

thanks for the response.. but it didn't work.. let me explain a bit more. I am generating a table in php with the following columns. 1. Employee Name --> pulled from database table called 'employees' 2. Kg --> a text field to input the amount of Kg's 3. Rate for the month --> pulled from database table called 'scraprates' 4. Kg * Rate --> Here I want to multiply the Kg amount entered by the user with the rate and display in the column (there is no text box for this). I want this calculation to happen for the Onchange event of the Kg text box

skparwal Over a year ago

code is updated. now check it will work. i have checked on my machine.

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