PHP with onclick function

Question

I want to execute a javascript function from a php file

Like:

<?php

$type=0;
echo('<img onclick="alert('.$type.')" src="picture.jpg"/>');

?>

Result : ok everything is workin. Now i want to do it with a string:

<?php

$type='e';
echo('<img onclick="alert('.$type.')" src="picture.jpg"/>');

?>

Result : Uncaught ReferenceError: e is not definedonclick @ loadPlayer2.php:2

<?php

$type='e';
echo('<img onclick="alert("'.$type.'")" src="picture.jpg"/>');

?>

Result : Uncaught SyntaxError: Unexpected token }

    <?php

$type='e';
echo('<img onclick="alert(\"'.$type.'\")" src="picture.jpg"/>');

    ?>

Result : Uncaught SyntaxError: Unexpected token ILLEGAL

<?php

$type='\e';

echo('<img onclick="alert("$type")" src="picture.jpg"/>');



?>

Result : Uncaught SyntaxError: Unexpected token }

mario · Accepted Answer · 2015-09-06 01:47:32Z

Different contexts require different escaping. You are mixing PHP strings with HTML attributes and JavaScript strings.

String interpolation only works in double quotes:

          alternate single+dbl quotes
                     ↓
  echo "<img onclick='alert(\"$type\")' src='picture.jpg'>"
                            ↑
                     escaped quote

The $type variable can be transformed from a PHP String to a JS string per json_encode:

  $type = json_encode($type);
  echo "<img onclick='alert($type)' src='picture.jpg'>"
                              ↑
            adds "double" quotes automatically

And it's best to apply htmlspecialchars for the whole attribute:

  $type = json_encode($type);
  $onclick = htmlspecialchars("alert($type)");
  echo "<img onclick='$onclick' src='picture.jpg'>"
                         ↑
            escapes `"` into `&quot;`

So the resulting output should look like:

   <img onclick='alert(&quot;\\e&quot;)' src='picture.jpg'>
                                                          ↑
                                                  pseudo-XHTML begone

And at this point, one could even use " for the attribute values again.

sachaamm · Accepted Answer · 2015-09-06 01:41:22Z

0

SOLVED:

<?php

$type="e";

echo('<img onclick="alert(\''.$type.'\')" src="picture.jpg"/>');


?>

answered Sep 6, 2015 at 1:41

sachaamm

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