Click the link, add text to textarea?

Question

Let's say I have this javascript:

<script language="javascript" type="text/javascript">
function addtext() {
    var newtext = document.myform.inputtext.value;
    document.myform.description.value += newtext;
}
</script>

and I want to enable it, so I can click on the html link that says “add text” and I want the text to be @. $ username. (using PHP to insert username). Therefore, when you click the add text link, it will be placed in the @username text box. It's hard to imagine, and I'm not sure where to place the text and PHP exactly. Thanks!

Textarea:

    <form Name ="myform" action="<?$posted = $_POST['description'];
    $object->post_tweet($posted); ?>" method="post">
    <table align="left" border="0" cellspacing="1" cellpadding="5">
      <tr>

        <td class="2">
     <textarea name='description' class="color" COLS=84 ROWS=2 type="text" id="eBann" name="bannerURL" maxlength="100" size="60" onKeyUp="toCount('eBann','sBann','{CHAR} characters left',140);"></textarea>
    <br>
      <span id="sBann" class="minitext">140 characters left.</span>
    </td>
  </tr>
</table><BR><BR><BR>
<p><input type='submit' value='Tweet!' /><input type='hidden' value='1' name='submitted' /> </p>
</form> 

This is what I want to do with the link:

<a href="#" onclick="addtext("@'. $twit->user->screen_name .'"); return false>reply</a>'

This gives me an error (I added the addtext function too).

EDIT: Got it! I had mistakes with 'and' ha ha wow, stupid mistake. Thanks everyone!

Answer 1

, . mish-mash HTML, JavaScript PHP, ?

<script language="javascript" type="text/javascript">
function addtext(text) {
    document.myform.description.value += text;
}
</script>

...

<a href="#" onclick="addtext('@<?php echo htmlspecialchars(addslashes($userName)) ?>'); return false"
  >reply</a>

: $userName is "TeaCast". HTML, <?php ?> , :

<a href="#" onclick="addtext('@TeaCast'); return false"
  >reply</a>

!

:

• href="#" , , .
• addslashes() PHP .
• htmlspecialchars() , , , '<' '&', . , - , "<script>alert('haha')</script>" (, HTML).

Answer 2

, , , javascript, :

<script language="javascript" type="text/javascript">
var username = '<?php echo htmlspecialchars(addslashes($userName)) ?>';

function addtusername() {
    document.myform.description.value += "@" + username;
}
</script>

...

<a href="#" onclick="addusername(); return false">reply</a>

, Javascript , , php.