PHP: Passing variable to javascript

Question

I am having a problem with a simple php file in which I am trying to pass a variable from php to javascript. I have used the exact same code successfully in a more complex program, but cannot get it to work in the most trivial context here. Below is the entire code. When I run it, it complains that xxx is an unidentified variable:

<?php
    echo "<h2 style='text-align: center'>Welcome</h2><br>";
    echo '<script>var xxx = "Hello";</script>'
?>

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8" />
        <title></title>
    </head>
    <body>
        <script>
            echo xxx;
        </script>
    </body>
</html>

I know there are other ways to pass data from php to js, but this one is simplest and I have used it before. Why is it failing here?

Additionally, it is invalid HTML to have output before the DOCTYPE. — Khalos
– Khalos, Commented Jul 16, 2015 at 1:30

epascarello · Accepted Answer · 2015-07-16 01:23:01Z

3

You are mixing php and JavaScript syntax

<script>
    echo xxx;
</script>

needs to be

<script>
   console.log(xxx);
</script>

ANd the php code should be in the body if you are outputting HTML.

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8" />
        <title></title>
    </head>
    <body>
<?php
    echo "<h2 style='text-align: center'>Welcome</h2><br>";
    echo '<script>var xxx = "Hello";</script>'
?>
        <script>
            console.log(xxx);
        </script>
    </body>
</html>

answered Jul 16, 2015 at 1:23

epascarello

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Comments

Lee Lee · Accepted Answer · 2015-07-16 01:41:06Z

0

This is how you can pass the value. Use ID as the parameter.

  <script>
            window.onload = function () {
                document.getElementById('NO').onchange = disablefield;
                document.getElementById('YES').onchange = disablefield;
        }</script>
echo "<tr><td width='50%'><input type='radio' name='item' value='A' id='YES'>YES</td><td><input type='radio' name='item' value='B' id='NO'>NO</td></tr>";

answered Jul 16, 2015 at 1:41

Lee Lee

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