【Base64 Encoding / Decoding in Node.js】
Here is how you encode normal text to base64 in Node.js:
var b = new Buffer('JavaScript');
var s = b.toString('base64');
// SmF2YVNjcmlwdA==
And here is how you decode base64 encoded strings:
var b = new Buffer('SmF2YVNjcmlwdA==', 'base64')
var s = b.toString();
// JavaScript
If you are interested in the details of how the above examples worked, follow me.
The new Buffer() constructor requires a number, array or string as the first parameter, and an optional encoding type as the second parameter. The possible encoding types are ascii, utf8, ucs2, base64, binary, and hex; the default being utf8.
By passing the second parameter, we tell JavaScript that "the string you see is encoded in this particular format". Notice how we did that in the decoding example.
Once we have the encoded string, we call the toString() method on the string. If we don't pass the encoding type to toString(), JavaScript assumes we want to convert the object to utf8 encoded string by default. We can make it convert to other formats by passing the encoding type totoString().
参考：http://www.hacksparrow.com/base64-encoding-decoding-in-node-js.html