I have a submit form in the forum (PHPBB):

HTML Code:
<form id="postform" method="post" action="./posting.php?mode=post&amp;f=1" enctype="multipart/form-data"> 
<div id="message-box"> 
<textarea name="message" id="message" rows="15" cols="76" tabindex="4" class="inputbox"></textarea> 
<input type="submit" accesskey="s" tabindex="6" name="post" value="Submit" class="button1 default-submit-action" />
And special javascript using API:

VK.api('wall.post',{ message: "Here must be text from the submit form", attachment: "" },function(data) { });
Its necessary to copy a text from the submit form (textarea name="message" id="message") to the value of 'message' for the above javascript when you click on the Submit button.

Any ideas? JS-parser? Ajax? Thanx