Using php variable in javascript if-statement

Question

I would like to pass on a $_POST['foo'] variable to a JavaScript variable while I am using a php if- statement. But its not working. Any suggestions on how to make it run?

<?php
if(isset($_POST['foo']))    
{    
?>
<script>
var jFoo= <?php echo json_encode($_POST['foo']); ?>;
</script>
<?
}


 else {
    ...
    }
    ?>

EDIT:

This is weird: I was actually trying to make the code run like this (this wasnt working):

if(isset($_POST['foo']))    
{    
?>
<script>
var jFoo= <?php echo json_encode($foo); ?>;
</script>
<?
}
else {
...
}

However, when I just did this, it worked:

<?php
if(isset($_POST['foo']))    
{    
?>
<script>
var jFoo= <?php echo json_encode($_POST['foo']); ?>;
</script>
<?
}
else {
...
}

Any ideas why?

Have you looked at the output HTML? Is it missing quote marks? — rybo111
– rybo111, Commented Sep 7, 2014 at 18:50
I don't see anything wrong with the code you posted. Why doesn't it work? What errors do you get? What is the output from your PHP script? — Brad
– Brad, Commented Sep 7, 2014 at 18:50
Posted variables are usually strings so you will need to change your code to var jFoo="<?php echo json_encode($_POST['foo']); ?>"; — user2417483
– user2417483, Commented Sep 7, 2014 at 18:50
@jeff That's completely incorrect. The JSON-encoding handles any quoting that is needed. Adding additional quotes actually breaks this. — Brad
– Brad, Commented Sep 7, 2014 at 18:50

subas_poudel · Accepted Answer · 2014-09-07 19:26:01Z

2

I made a simple change in your script and it works for me. I changed the code in line 9 from

<?php
if(isset($_POST['foo']))    
{    
?>
<script>
var jFoo= <?php echo json_encode($_POST['foo']); ?>;
alert(jFoo);
</script>
<?php
}
else {

}
?>

<form action="" method="post">
    <input type="text" name='foo' />
    <button type="submit">Submit</button>
</form>

edited Sep 7, 2014 at 19:26

answered Sep 7, 2014 at 19:10

subas_poudel

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Comments

William Pereira · Accepted Answer · 2014-09-07 19:21:29Z

1

This code works normally:

        <form method="post" action="">
             <input type="text" name="foo"></input>
             <input type="submit" name="submit" value="submit">
        </form>
        <script type="text/javascript">
           <?php
              if(isset($_POST['foo'])) {
           ?>
           var jFoo = <?php echo json_encode($_POST['foo']); ?>;
           alert(jFoo); // test
           <?php } ?>
        </script>

edited Sep 7, 2014 at 19:21

answered Sep 7, 2014 at 19:04

William Pereira

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