JS copy specific content to paste board

<script language="javascript">
function readTxt()
{
alert(("text"));
}
function setTxt()
{
var t=("txt");
();
('text',().text);
}
</script>
<input name="txt" value="test">
<input type="button" value="Copy" onclick="setTxt()">
<input type="button" value="read" onclick="readTxt()">