PHP Echoing JSON string into HTML Input value - Need character escape

Question

Here is a simplified version of my code that I am having a problem with.

$variable = "{\\\"JSON" //long JSON string created in Javascript with JSON.stringify
?> <input type="text" name="somename" value="<?php echo $variable; ?>"/> <?php

The input box only contains {\\ I need a way to escape the entire JSON string

Thanks Alex

Answer 1

You're outputting into an HTML context, so you need html-specific escaping:

<input ... value="<?php echo htmlspecialchars(json_encode($whatever)); ?>" />
                             ^^^^^^^^^^^^^^^^----

Answer 2

$val= json_encode($val);

<input type="hidden" value="<?php echo htmlspecialchars($val); ?>" name="bye">