diff --git a/src/blake.js b/src/blake.js
--- a/src/blake.js
+++ b/src/blake.js
@@ -9,6 +9,11 @@ function rrot(x,shift){
 	return ((x>>>shift)|(x<<(32-shift)))&MASK;
 }
 
+/**
+ * @param {number} outputLen output length in bytes, 1<=x<=32
+ * @param {Array} key byte array, 0<=key.length<=32
+ * @returns {BLAKE2S}
+ */
 export function BLAKE2S(outputLen=32,key=[]){
 	this._buffer=[];
 	this._dataLen=[0,0]; // low, high