js 人民币小写金额转换为大写

function smalltoBIG(n) {
    var fraction = ['角', '分'];
    var digit = ['零', '壹', '贰', '叁', '肆', '伍', '陆', '柒', '捌', '玖'];
    var unit = [
        ['元', '万', '亿'],
        ['', '拾', '佰', '仟']
    ];
    var head = n < 0 ? '欠' : '';
    n = Math.abs(n);
 
    var s = '';
 
    for (var i = 0; i < fraction.length; i++) {
        s += (digit[Math.floor(n * 10 * Math.pow(10, i)) % 10] + fraction[i]).replace(/零./, '');
    }
    s = s || '整';
    n = Math.floor(n);
 
    for (var i = 0; i < unit[0].length && n > 0; i++) {
        var p = '';
        for (var j = 0; j < unit[1].length && n > 0; j++) {
            p = digit[n % 10] + unit[1][j] + p;
            n = Math.floor(n / 10);
        }
        s = p.replace(/(零.)*零$/, '').replace(/^$/, '零') + unit[0][i] + s;
    }
    return head + s.replace(/(零.)*零元/, '元').replace(/(零.)+/g, '零').replace(/^整$/, '零元整');
}
console.log(smalltoBIG(5165165.68));