accessing local var value from JS function in PHP - php

Question

After searching for internet and even here for 5 hours, i am still stuck at getting value of a local variable in a function and sending it to PHP.
I have tried different syntaxes but none of them seems to be working. This code below, takes an input field from PHP and assign some value to it (having problem send this value back to PHP)
$(document).ready(function() {
//select all the a tag with name equal to modal
$('form[name=modal]').click(function(e) {
//Cancel the link behavior
e.preventDefault();
//Dont go until value is not 7
console.log('i am Now waiting for input');
var s = $('#serial').val();
console.log('searching for ' + s);
while(s.length != 7) return;
//When code value reaches 7
var code = $('#serial').val();
console.log('Value is reached ' + s);
});
});
In PHP
echo "<script>document.write(code);</script>";
Uncaught ReferenceError: code is not defined
please help

Answer 1

You should do somthing like this in javascript when $('#serial') is your input field.
$.ajax({'url':'your_php_file_url', 'type':'post', 'data':{'str':$('#serial').val()}}).done(function(data){
console.log(data.code);
});
And in php
$output = Array('code' => 'not set');
if (isset($_POST['str']))
{
//do your search and assigne value to output
$output['code'] = 'some value';
}
echo json_encode($output);
In short - you send your search string via ajax to php and make your searches. Then you echo it out as json, then ajax will read it as an object and you can use those values you want.

Answer 2

ok, i have almost tested every possible solution but all in vain... so i am off and try to use some normal method rather than javascript. Thanks for all your answers guys.