GLib.base64_decode

function base64_decode(text: String): [return_value: ByteArray, out_len: Number(gsize)] {
    // Gjs wrapper for g_base64_decode()
}

Decode a sequence of Base-64 encoded text into binary data. Note that the returned binary data is not necessarily zero-terminated, so it should not be used as a character string.

Since 2.12

text: zero-terminated string with base64 text to decode
return_value: newly allocated buffer containing the binary data that text represents. The returned buffer must be freed with GLib.free.
out_len: The length of the decoded data is written here