diff --git a/utils.js b/utils.js
index f6a2e1c..cf54bea 100644
--- a/utils.js
+++ b/utils.js
@@ -1,11 +1,24 @@
 import { class_ } from "./main.js";
 
+/**
+ * async wait/pause function
+ * 
+ * @param {number} ms 
+ * @returns 
+ */
 export const wait = (ms) => {
     return new Promise((res, rej) => {
         setTimeout(res, ms);
     });
 }
 
+/**
+ * fadeout an Element.
+ * 
+ * @param {HTMLElement|class_} Selems Element ot fade
+ * @param {number} [ms] Duration in ms
+ * @param {boolean} [force] 
+ */
 export const fadeout = async (Selems, ms = 200, force = false) => {
     var oldTrans = [];
     if (!Array.isArray(Selems)) Selems = [Selems];
@@ -29,6 +42,15 @@ export const fadeout = async (Selems, ms = 200, force = false) => {
         elems[i].style.transition = oldTrans[i];
     }
 }
+
+/**
+ * fadein an Element.
+ * 
+ * @param {HTMLElement|class_} Selems Element to fade
+ * @param {number} [ms] Duration in ms
+ * @param {boolean} [force] 
+ * @param {string} [display] Set destroyed display style tag.
+ */
 export const fadein = async (Selems, ms = 200, force = false, display="") => {
     var oldTrans = [];
     if (!Array.isArray(Selems)) Selems = [Selems];
@@ -53,6 +75,12 @@ export const fadein = async (Selems, ms = 200, force = false, display="") => {
 }
 
 var bStack = [];
+/**
+ * The callback will be triggered when the user intends to go back.
+ * 
+ * @param {function} callback
+ * @returns {function} cancle callback
+ */
 export const subCancel = (callback) => {
     bStack.push(callback);
     return ()=>{