学步园

<script> 
function cc(s){ 
        if(/[^0-9\.]/.test(s)) return "invalid value"; 
        ss=s.replace(/^(\d*)$/,"$1."); 
        s=(s+"00").replace(/(\d*\.\d\d)\d*/,"$1"); 
        ss=s.replace(".",","); 
        var re=/(\d)(\d{3},)/; 
        while(re.test(s)) 
                ss=s.replace(re,"$1,$2"); 
        ss=s.replace(/,(\d\d)$/,".$1"); 
        return "￥" + s.replace(/^\./,"0.") 
        } 
</script> 
<input onchange="this.value=cc(this.value)">