To Fetch FORM Element value directly in JAVASCRIPT

Below example show how to fetch Form Element value directly in Javascript without use of Document.form

JAVASCRIPT:
<script language="javascript">
function checkTestForm()
{
    with (window.document.frmTest)
    {
        alert(txtPrice.value);       
    }
   
}
</script>

HTML CODE:
<form id="frmTest" name="frmTest" method="post">
<input type="text" id="txtPrice" name="txtPrice" />
<input type="button" id="btn" name="btn"  value="OK"   onclick="return checkTestForm();" />
</form>