/**
 * 強制保留2位小數，不足補 0 
 */
function toDecimal(x) {    
        var f = parseFloat(x);    
        if (isNaN(f)) {    
            return false;    
        }    
        var f = Math.round(x*100)/100;    
        var s = f.toString();    
        var rs = s.indexOf('.');    
        if (rs < 0) {    
            rs = s.length;    
            s += '.';    
        }    
        while (s.length <= rs + 2) {    
            s += '0';    
        }    
        return s;    
    }