js數字轉為保留兩位有效數字的小數

function toDecimal(x) {
    if (x !== '.') {
        let f = Math.round(x * 100) / 100;
        let s = f.toString();
        let rs = s.indexOf('.');
        if (rs <= 0) {
            rs = s.length;
            s += '.';
        }
        while (s.length <= rs + 2) {
            s += '0';
        }
        return s;
    } else {
        return '0.00';
    }
}