如何在javascript变量中获取php文件的结果

I want to append the myadd.php file result to textarea. Code is as shown below:

<textarea name="_to" spellcheck="false" id="_to" cols="70" rows="1" tabindex="2" autocomplete="off"></textarea>
<button type="submit" form="SubmitForm" onclick="loadSubmitResults('_to');">Submit</button>

<script language="javascript" type="text/javascript">
var urn='wdr';
function loadSubmitResults(to) {
var obj=document.getElementById(to);
var att = $().load('myadd.php?h='+urn);
obj.value+=att;
}
</script>

How does I should append the result of myadd.php file after typing some text in textarea?

Try this:

function loadSubmitResults(to) {
    var el = document.getElementById(to);
    $.get('myadd.php', { h: urn }, function(result){
        el.value += result;
    });
}

and change this:

onclick="loadSubmitResults('_to'); return false;"