how to set value in text area - php

Question

I'm working on the playground using from codemirror.net, and is works great. My next step is to have auto load set a value to file path name, each textarea will load file path from .html, .css and jquery.
currently in codemirror showing
<div id="wrap">
<!-- Code Editors --> <section id="code_editors">
<div id="html" class="code_box">
<h3>HTML</h3>
<textarea name="html"></textarea>
</div>
<div id="css" class="code_box">
<h3>CSS</h3>
<textarea name="css"></textarea>
</div>
<div id="js" class="code_box">
<h3>JavaScript</h3>
<textarea name="js"></textarea>
</div> </section>
<!-- Sandboxing --> <section id="output">
<iframe></iframe> </section> </div>
The result of preview textarea showed "Hello world" that because in javascript showed
html_editor.setValue('<p>Hello World</p>');
css_editor.setValue('body { color: red; }');
so i change set value in codemirror like this.
<textarea name="html"><?php
echo file_get_contents('testcode.php');
?>
</textarea>
</div>
this works great when I see HTML code inside of text area but unable to see the preview in the text area.
so I'm trying to solve this how to see preview too using
<?php echo file_get_contents('testcode.php');?>
I thought to make change in javascript where it said
html_editor.setValue('<p>Hello World</p>');
css_editor.setValue('body { color: red; }');
my question is that how can I write code in PHP inside of javascript file.
i tried
html_editor.setValue('<?php echo file_get_contents('testcode.php');?>');
css_editor.setValue('body { color: red; }');
it does not work.
Any other idea how to solve this to make both works!
many thanks.
AM

Answer 1

Try this :
var = "<?php echo file_get_contents('testcode.php')?>";
html_editor.setValue(var );
css_editor.setValue('body { color: red; }');