How can I use a JavaScript variable as a PHP variable? [duplicate]

Solution 1:

PHP is run server-side. JavaScript is run client-side in the browser of the user requesting the page. By the time the JavaScript is executed, there is no access to PHP on the server whatsoever. Please read this article with details about client-side vs server-side coding.

What happens in a nutshell is this:

• You click a link in your browser on your computer under your desk
• The browser creates an HTTP request and sends it to a server on the Internet
• The server checks if he can handle the request
• If the request is for a PHP page, the PHP interpreter is started
• The PHP interpreter will run all PHP code in the page you requested
• The PHP interpreter will NOT run any JS code, because it has no clue about it
• The server will send the page assembled by the interpreter back to your browser
• Your browser will render the page and show it to you
• JavaScript is executed on your computer

In your case, PHP will write the JS code into the page, so it can be executed when the page is rendered in your browser. By that time, the PHP part in your JS snippet does no longer exist. It was executed on the server already. It created a variable $result that contained a SQL query string. You didn't use it, so when the page is send back to your browser, it's gone. Have a look at the sourcecode when the page is rendered in your browser. You will see that there is nothing at the position you put the PHP code.

The only way to do what you are looking to do is either:

• do a redirect to a PHP script or
• do an AJAX call to a PHP script

with the values you want to be insert into the database.

Solution 2:

<script type="text/javascript">
var jvalue = 'this is javascript value';

<?php $abc = "<script>document.write(jvalue)</script>"?>   
</script>
<?php echo  'php_'.$abc;?>

Solution 3:

You seem to be confusing client-side and server side code. When the button is clicked you need to send (post, get) the variables to the server where the php can be executed. You can either submit the page or use an ajax call to submit just the data. -don

Solution 4:

PHP runs on the server. It outputs some text (usually). This is then parsed by the client.

During and after the parsing on the client, JavaScript runs. At this stage it is too late for the PHP script to do anything.

If you want to get anything back to PHP you need to make a new HTTP request and include the data in it (either in the query string (GET data) or message body (POST data).

You can do this by:

• Setting location (GET only)
• Submitting a form (with the FormElement.submit() method)
• Using the XMLHttpRequest object (the technique commonly known as Ajax). Various libraries do some of the heavy lifting for you here, e.g. YUI or jQuery.

Which ever option you choose, the PHP is essentially the same. Read from $_GET or $_POST, run your database code, then return some data to the client.