/^(d*.d{0,2}|d+).*$/

!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
html xmlns="http://www.w3.org/1999/xhtml">
head>
meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
title>無標題文檔/title>
script type="text/javascript">
function checkPrice(me){
if(!(/^(?:d+|d+.d{0,2})$/.test(me.value))){
me.value = me.value.replace(/^(d*.d{0,2}|d+).*$/,'$1');
}
}
/script>
/head>
body>
input type="text" onkeyup="checkPrice(this);"/>
/body>
/html>