js 数字转为中文

function numberToChinese(num) {
  const digits = ['零', '一', '二', '三', '四', '五', '六', '七', '八', '九'];
  const units = ['', '十', '百', '千'];
  const higherUnits = ['', '万', '亿'];

  if (num === 0) return digits[0];

  let str = '';
  let unitPos = 0;
  let higherUnitPos = 0;

  while (num > 0) {
    const section = num % 10000;
    let sectionStr = '';
    let zeroFlag = false;

    for (let i = 0; i < 4; i++) {
      const digit = section % 10;
      if (digit === 0) {
        zeroFlag = true;
      } else {
        if (zeroFlag) {
          sectionStr = digits[0] + sectionStr;
          zeroFlag = false;
        }
        sectionStr = digits[digit] + units[i] + sectionStr;
      }
      section = Math.floor(section / 10);
    }

    if (sectionStr !== '') {
      str = sectionStr + higherUnits[higherUnitPos] + str;
    } else if (str !== '' && !str.startsWith(digits[0])) {
      str = digits[0] + str;
    }

    num = Math.floor(num / 10000);
    higherUnitPos++;
  }

  // 处理特殊情况，如一十 -> 十
  if (str.startsWith('一十') && str.length === 2) {
    str = str.substring(1);
  }

  return str;
}

console.log(numberToChinese(123456789)); // 一亿二千三百四十五万六千七百八十九