如何将node.js中的位串转成base64？

Question

我有一个要转换为 base64 的位字符串，但看起来没有执行此操作的本机函数，而且我也找不到节点模块。 ):

输入：100110110101000110100011011001100010110100011011001100100110100011000001100000110000011000001100001001010100111110000011001111100101010011111010011100010110001001001001100000110100111010010100111110000111001000100000110001001000101100111110011001001001101011010001011001001101001010000011000100100100110000011010011

输出：等效二进制值的 base64 表示

也许更好的问题是如何将位串转换成缓冲区？不确定

Answer 1

如您所料，主要是将字符串转换为更容易转换为 base64 的内容，然后再将其转换为 base64。

在下面的代码中，我们执行这些转换序列：

位字符串 -> BigInt -> 字节大小的整数数组 -> 二进制字符串 -> base64
base64 -> 二进制字符串 -> 字节大小的位串数组 -> 位串

const encode = bitstr => {
  const bytes = [];
  // convert bit string to BigInt
  let value = BigInt('0b' + bitstr);
  // chop it up into bytes
  while (value > 0n) {
    bytes.unshift(Number(value & 0xffn));
    value >>= 8n;
  }
  // convert to binary string and encode as base64
  return btoa(String.fromCharCode.apply(null, bytes));
};

const decode = b64 => {
  // decode base64 to binary string
  const bstr = atob(b64);
  // convert binary string to bit string
  return new Array(bstr.length).fill(0).map(
    (_,i) => bstr.charCodeAt(i).toString(2).padStart(8, i ? '0' : '')
  ).join('');
};

const bitstr = '100110110101000110100011011001100010110100011011001100100110100011000001100000110000011000001100001001010100111110000011001111100101010011111010011100010110001001001001100000110100111010010100111110000111001000100000110001001000101100111110011001001001101011010001011001001101001010000011000100100100110000011010011';
const encoded = encode(bitstr);
const decoded = decode(encoded);

console.log(bitstr);
console.log(encoded);
console.log(decoded);

如何将node.js中的位串转成base64？

How to convert a bit string to base64 in node.js?

javascript

binary

base64

bit-manipulation

node.js