中文编码问题，​使用SHA256时原始字符串中有中文，导致和后端算出的结果不一致，该怎么解决？

// 字符串转成字节流 
function stringToUint8ArrayByte(str: string) { 
  return new Uint8Array(buffer.from(str,'utf-8').buffer); 
} 
// 字节流转成可理解的字符串 
function uint8ArrayToStringByte(array:Uint8Array) { 
  // 将UTF-8编码转换成Unicode编码 
  let out: string = ''; 
  let index: number = 0; 
  let len: number = array.length; 
  while (index < len) { 
    let character = array[index++]; 
    switch(character >> 4) { 
      case 0: 
      case 1: 
      case 2: 
      case 3: 
      case 4: 
      case 5: 
      case 6: 
      case 7: 
        out += String.fromCharCode(character); 
        break; 
      case 12: 
      case 13: 
        out += String.fromCharCode(((character & 0x1F) << 6) | (array[index++] & 0x3F)); 
        break; 
      case 14: 
        out += String.fromCharCode(((character & 0x0F) << 12) | ((array[index++] & 0x3F) << 6) | ((array[index++] & 0x3F) << 0)); 
        break; 
      default: 
        break; 
    } 
  } 
  return out; 
}