在node.js中的base64解码/编码中指定“替代字符”

Question

I am trying to port some code from python to node. The code is as follows:

//returns the UID contained in the var uid decoded to an int:
uid = 'ABCDE'
struct.unpack(">I", base64.b64decode(uid + 'A==', "[]"))[0] / 4

//encodes the UID int in uidint into the B64 UID:
uidint = 270532
base64.b64encode(struct.pack(">I", uidint * 4), "[]")[0:5]

I have already found a library that replaces the pack/unpacking functionality provided by python's struct class.

However, python's implementation of base64 has support for allowing alternate characters. Unfortunately, node's does not.

Here is my work-in-progress port:

uid = 'ABCDE';
decoded = new Buffer(uid+'A==', 'base64').toString('ascii');
console.log(decoded);
test = jspack.Unpack(">I",decoded)[0] / 4;
console.log(test);

Currently the first console.log returns weird characters. the second returns NaN. Which makes sense why it'd do that.

I was wondering if anyone knew how to replicate python's implementation of this pattern. I've been scanning through libraries on npm and didn't find anything that might suggest this as a feature.

Answer 1

Just replace them manually before creating buffer:

new Buffer(
  (uid+'A==')
    .replace(/\+/g, '[')
    .replace(/\//g, ']')
, 'base64').toString('ascii')