diff --git a/cmd/gtree-wasm/Makefile b/cmd/gtree-wasm/Makefile
index 07bdf6b..bde10e4 100644
--- a/cmd/gtree-wasm/Makefile
+++ b/cmd/gtree-wasm/Makefile
@@ -24,6 +24,7 @@ deploy: confirm tinybuild
 	cleancss -o ../../docs/toast.css toast.css
 	uglifyjs main.js --compress drop_console=true -o ../../docs/main.js
 	uglifyjs toast.js --compress drop_console=true -o ../../docs/toast.js
+	uglifyjs tab.js --compress drop_console=true -o ../../docs/tab.js
 	uglifyjs wasm_exec.js --compress drop_console=true -o ../../docs/wasm_exec.js
 	cp index.html service_worker.js robots.txt sitemap.xml ../../docs
 	mv main.wasm ../../docs
diff --git a/cmd/gtree-wasm/confirm.sh b/cmd/gtree-wasm/confirm.sh
index cd82f7d..f63a626 100644
--- a/cmd/gtree-wasm/confirm.sh
+++ b/cmd/gtree-wasm/confirm.sh
@@ -1,6 +1,6 @@
 #!/bin/sh
 
-echo -n "service_worker.js の CACHE_VERSION 変数を更新しましたか? [y/N]: "
+echo -n "service_worker.js の CACHE_VERSION 変数の変更/ 新規作成したjsファイルを urlsToCache に追加しましたか? [y/N]: "
 read ANS
 
 case $ANS in
diff --git a/cmd/gtree-wasm/index.html b/cmd/gtree-wasm/index.html
index 1e387b7..c8f922a 100644
--- a/cmd/gtree-wasm/index.html
+++ b/cmd/gtree-wasm/index.html
@@ -98,6 +98,7 @@ <h1 class="text-3xl font-bold">
   </div>
 
   <script src="toast.js"></script>
+  <script src="tab.js"></script>
 
   <script>
     // register service_worker.js
diff --git a/cmd/gtree-wasm/main.js b/cmd/gtree-wasm/main.js
index 367bcd2..cf2ab6f 100644
--- a/cmd/gtree-wasm/main.js
+++ b/cmd/gtree-wasm/main.js
@@ -26,4 +26,3 @@ const copyToClipboard = () => {
   const clipboard = window.navigator.clipboard;
   clipboard.writeText(tree.innerHTML);
 };
-
diff --git a/cmd/gtree-wasm/service_worker.js b/cmd/gtree-wasm/service_worker.js
index 672fcdb..722f30c 100644
--- a/cmd/gtree-wasm/service_worker.js
+++ b/cmd/gtree-wasm/service_worker.js
@@ -1,7 +1,7 @@
 // copied by https://laboradian.com/create-offline-site-using-sw/
 
 // TODO: ファイル変更したらCACHE_VERSIONを変えてデプロイすること
-const CACHE_VERSION = 'v1.1.3';
+const CACHE_VERSION = 'v1.1.4';
 const CACHE_NAME = `${registration.scope}!${CACHE_VERSION}`;
 
 // キャッシュするファイルをセットする
@@ -12,6 +12,7 @@ const urlsToCache = [
   'toast.css',
   'main.js',
   'toast.js',
+  'tab.js',
   'wasm_exec.js',
 ];
 
diff --git a/cmd/gtree-wasm/tab.js b/cmd/gtree-wasm/tab.js
new file mode 100644
index 0000000..5966bd6
--- /dev/null
+++ b/cmd/gtree-wasm/tab.js
@@ -0,0 +1,19 @@
+// ref: http://www.webclap-dandy.com/?category=Programing&id=5
+const tabKey = 9;
+const spaces = '  ';
+const onTabKey = (e) => {
+  if (e.keyCode != tabKey){ return; };
+
+  e.preventDefault();
+
+  const cursor = e.target;
+  const currStr = String(cursor.value);
+
+  const position = cursor.selectionStart;
+  const left = currStr.substring(0, position);
+  const right = currStr.substring(position, currStr.length);
+
+  cursor.value = left + spaces + right;
+  cursor.selectionEnd = position + spaces.length;
+};
+document.getElementById('in').onkeydown = (e) => onTabKey(e);
diff --git a/docs/index.html b/docs/index.html
index 1e387b7..c8f922a 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -98,6 +98,7 @@ <h1 class="text-3xl font-bold">
   </div>
 
   <script src="toast.js"></script>
+  <script src="tab.js"></script>
 
   <script>
     // register service_worker.js
diff --git a/docs/service_worker.js b/docs/service_worker.js
index 672fcdb..722f30c 100644
--- a/docs/service_worker.js
+++ b/docs/service_worker.js
@@ -1,7 +1,7 @@
 // copied by https://laboradian.com/create-offline-site-using-sw/
 
 // TODO: ファイル変更したらCACHE_VERSIONを変えてデプロイすること
-const CACHE_VERSION = 'v1.1.3';
+const CACHE_VERSION = 'v1.1.4';
 const CACHE_NAME = `${registration.scope}!${CACHE_VERSION}`;
 
 // キャッシュするファイルをセットする
@@ -12,6 +12,7 @@ const urlsToCache = [
   'toast.css',
   'main.js',
   'toast.js',
+  'tab.js',
   'wasm_exec.js',
 ];
 
diff --git a/docs/tab.js b/docs/tab.js
new file mode 100644
index 0000000..d723094
--- /dev/null
+++ b/docs/tab.js
@@ -0,0 +1 @@
+const tabKey=9,spaces="  ",onTabKey=e=>{var position,left,currStr;e.keyCode==tabKey&&(e.preventDefault(),e=e.target,currStr=String(e.value),position=e.selectionStart,left=currStr.substring(0,position),currStr=currStr.substring(position,currStr.length),e.value=left+spaces+currStr,e.selectionEnd=position+spaces.length)};document.getElementById("in").onkeydown=e=>onTabKey(e);
\ No newline at end of file