base64 JSON encoded strings in nodejs
var buff = new Buffer(JSON.stringify({"hello":"world"})).toString("base64");
To complete @ladenedge's comment for clarity reasons:
var buff = Buffer.from(JSON.stringify({"hello":"world"})).toString("base64")
You can always prettify above code by providing some spacing, so that when some one decode it back to JSON String it would look good.
var buff = Buffer.from(JSON.stringify({"hello":"world"},undefined,n)).toString("base64")
n = 1 to 10 (Spacing)