学习使用js实现数字转大写和大额数字转换万、千万、亿、万亿等单位的方法

function toCapital(n) {
    const fraction = ['角', '分'];
    const digit = ['零', '壹', '贰', '叁', '肆', '伍', '陆', '柒', '捌', '玖'];
    const unit = [
        ['元', '万', '亿'],
        ['', '拾', '佰', '仟']
    ];
    let head = n < 0 ? '负' : '';
    n = Math.abs(n);
    let s = '';

    function toWan(n) {
        let wan = Math.floor(n / 10000);
        let yi = n % 10000;
        if (wan) {
            s += (digit[wan] + unit[0][0])
                .replace('零', '')
                .replace('一', '十')
                .replace(/零$/, '');
            s += (yi ? toYi(yi) : unit[0][0]) + unit[1][1];
        } else {
            s += toYi(yi) || '零';
        }
        return s;
    }

    function toYi(n) {
        let qian = Math.floor(n / 1000);
        let bai = n % 1000;
        s += (qian ? (digit[qian] + unit[0][2]).replace('零', '') : '');
        s += toBai(bai);
        return s;
    }

    function toBai(n) {
        let shi = Math.floor(n / 100);
        let ge = n % 100;
        s += (shi ? (digit[shi] + unit[1][2]).replace('零', '') : '');
        s += (ge ? (digit[ge] + unit[1][0]).replace('零', '') : '');
        return s;
    }

    s = toBai(Math.floor(n / 100)).replace('零', '');
    s += (n % 100 ? (digit[Math.floor(n % 100 / 10)] + fraction[0]).replace('零', '') : '');
    s += (n % 10 ? digit[n % 10] + fraction[1] : '整');
    return head + s;
}

// 使用示例
console.log(toCapital(0.11)); // 零角壹分
console.log(toCapital(123456789.99)); // 壹亿贰仟叁佰肆拾伍万陆仟伍拾拾元玖分