Facebook share with prefilled message

I have a page with a text area and would like to use a facebook share api so that the message that is written by the user in this text area is automatically prefilled in the message section of facebook share dialog. As I know, it is not forbidden by the policy of facebook (the case when the message was written by the user), but haven't found any examples in the docs.

<label for="message">Message</label>
<textarea id="message" placeholder="Please leave a short message"></textarea>

<div class="fb-share-button" data-href="https://someurl.com/" data-layout="button_count" data-size="small">
    <a target="_blank" href="https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fsomeurl.com%2F&amp;src=sdkpreparse" class="fb-xfbml-parse-ignore">Share</a>
</div>