[FIX] cross language compatible meta subject

[tothandras]

I'm opening this PR mainly to open a discussion around language cross compatibility (with Go). This would be a breaking change.
https://github.com/nats-io/nats.go/blob/f4102422df7df83b2032318fd14a248c45f113e1/object.go#L442

also related: nats-io/nats.py#331 (review)

[aricart]

Yes, this is a bug in the javascript client, the proposed fix doesn't work because Buffer is only available in the node.js ecosystem.

[tothandras]

oh, indeed! https://deno.land/std/encoding/base64url.ts should work, I'll replace the Buffer and try it out as well.

[aricart]

the solution has to work on a browser where std/encoding is not available.

[aricart]

class Base64Codec {
  static encode(bytes: string | Uint8Array): string {
    if (typeof bytes === "string") {
      return btoa(bytes);
    }
    const a = Array.from(bytes);
    return btoa(String.fromCharCode(...a));
  }

  static decode(s: string, binary = false): Uint8Array | string {
    const bin = atob(s);
    if (!binary) {
      return bin;
    }
    const bytes = new Uint8Array(bin.length);
    for (let i = 0; i < bin.length; i++) {
      bytes[i] = bin.charCodeAt(i);
    }
    return bytes;
  }
}

class Base64UrlCodec {
  static encode(bytes: string | Uint8Array): string {
    return Base64UrlCodec.toB64URLEncoding(Base64Codec.encode(bytes));
  }

  static decode(s: string, binary = false): Uint8Array | string {
    return Base64Codec.decode(Base64UrlCodec.fromB64URLEncoding(s), binary);
  }

  static toB64URLEncoding(b64str: string): string {
    b64str = b64str.replace(/=/g, "");
    b64str = b64str.replace(/\+/g, "-");
    return b64str.replace(/\//g, "_");
  }

  static fromB64URLEncoding(b64str: string): string {
    // pads are % 4, but not necessary on decoding
    b64str = b64str.replace(/_/g, "/");
    b64str = b64str.replace(/-/g, "+");
    return b64str;
  }
}

[aricart]

I'll put the above somewhere conventient

[tothandras]

@aricart Something like this b4cd346?

[aricart]

LGTM

[aricart]

@tothandras thanks for the contribution!