diff --git a/main.d.ts b/main.d.ts
index c6d7257..4f721fe 100644
--- a/main.d.ts
+++ b/main.d.ts
@@ -463,7 +463,7 @@ export namespace helper {
      * sync files to target directory from source directory
      * @param source 
      * @param target 
-     * @param ext default value is = '*'
+     * @param ext default value is = '*', js|ts ...
      * @param reback default value if true
      */
     function _sync(source: string, target: string, ext?: string, reback?: boolean): Promise<void>;
@@ -472,7 +472,7 @@ export namespace helper {
     * list files in some directory
     * @param dir 
     * @param full 
-    * @param ext 
+    * @param ext .js|.ts
     */
     function _list(dir: string, full?: boolean, ext?: string): Promise<string[]>;
 
@@ -520,7 +520,7 @@ export namespace helper {
     /**
     * search some files by extension
     * @param dir 
-    * @param ext 
+    * @param ext js|ts
     * @param recur 
     */
     function _search(dir: string, ext?: string, recur?: boolean): Promise<string[]>;
diff --git a/src/helper/fs.js b/src/helper/fs.js
index 37f2fe8..1b781c9 100644
--- a/src/helper/fs.js
+++ b/src/helper/fs.js
@@ -93,9 +93,8 @@ async function _copy(source, target, recur = false) {
 
 /**
  * search files in the directory
- * @example js|ts ...
  * @param {*} dir 
- * @param {*} ext 
+ * @param {*} ext js|ts ...
  * @param {*} recur 
  * @returns 
  */
@@ -122,10 +121,9 @@ async function _search(dir, ext = '*', recur = true) {
 
 /**
  * find files in the directory with deep one level
- * @example .js|.ts
  * @param {*} dir 
  * @param {*} full 
- * @param {*} ext 
+ * @param {*} ext .js|.ts
  * @returns 
  */
 async function _list(dir, full = false, ext = '*') {
@@ -191,10 +189,9 @@ async function _md5(filepath, charset = 'utf8') {
 
 /**
  * file system sync
- * @example js|ts ...
  * @param {*} source 
  * @param {*} target 
- * @param {*} ext 
+ * @param {*} ext js|ts ...
  * @param {*} reback 
  */
 async function _sync(source, target, ext = '*', reback = true) {