I want to use javascript variable as php variable. I am echo php variable then its print. but when i am use for fetching data from database its show an error Notice: Undefined index: document.write(i)
here my code
javascript
var i=0;
function inc()
{
i+=1;
}
<?php $foo="<script>document.write(i)</script>"; ?>
php
code work for
echo $foo
code not work for
$i=$foo;
$query="select * from TABLE where id = $i";
$result=mysqli_query($conn,$query);
while($row=mysqli_fetch_row($result))
{
echo $row[0];
}
Then It show This Error Notice: Undefined index: document.write(i)
PHP is server-side code that is run to generate a page. Javascript is client-side code that is run after the page is sent to the visitor's browser. Javascript can't affect the server-side code because the server code is done running by the time the Javascript runs. If you want to have a user's selection change the behavior of the PHP code the next time the form is loaded, pass a variable through a $_POST variable when the form is submitted.
If you want your PHP and Javascript code to be using the same value, have the PHP code write a Javascript variable initialization into the page's <head> section before any Javascript would run that would need to use it.
<script>
var i=0;
function inc()
{
i+=1;
return i;
}
</script>
<?php
$foo = '<script type="text/javascript">document.write(inc());</script>'; //Script function call which return the var i value to php variable
echo $foo;
?>