diff --git a/packages/playground/examples/bubble-sort.tsx b/packages/playground/examples/bubble-sort.tsx
new file mode 100644
index 0000000000..df2350b763
--- /dev/null
+++ b/packages/playground/examples/bubble-sort.tsx
@@ -0,0 +1,90 @@
+async function bubbleSort(arr, options) {
+  const max = arr.length - 1
+  for (let j = 0; j < max; j++) {
+    let done = true
+    for (let i = 0; i < max - j; i++) {
+      options.check(i, i + 1)
+      if (arr[i] > arr[i + 1]) {
+        await swap(arr, i, i + 1)
+        done = false
+      }
+    }
+    if (done) {
+      options.done(arr)
+      break
+    }
+  }
+  return arr
+}
+
+function swap(arr, indexA, indexB) {
+  return new Promise(resolve => {
+    setTimeout(() => {
+      const temp = arr[indexA];
+      arr[indexA] = arr[indexB]
+      arr[indexB] = temp
+      resolve()
+    }, 20)
+  })
+}
+
+class Store {
+  data = {
+    arr: [2, 7, 12, 9, 16, 19, 8, 13, 11, 5, 15, 17, 14, 18, 6, 3, 10, 1, 4],
+    indexA: -1,
+    indexB: -1,
+    sorting: false
+  }
+  sort = () => {
+    this.data.sorting = true
+    bubbleSort(this.data.arr, {
+      done: () => {
+        this.data.indexA = -1
+        this.data.indexB = -1
+        this.ui.update()
+      },
+      check: (indexA, indexB) => {
+        this.data.indexA = indexA
+        this.data.indexB = indexB
+        this.ui.update()
+      }
+    })
+  }
+}
+
+@tag('my-element')
+class extends WeElement {
+  static css = `
+    .bar {
+      display: inline-block;
+      margin-left: 1px;
+      background: #777;
+      width: 10px; 
+    }
+    
+    .active{
+      background: red;
+    }`
+
+  installed() {
+    this.store.ui = this
+  }
+
+  render(prop, store) {
+    return (
+      <div>
+        <div>
+          {store.data.arr.map((item, index) => (
+            <div class={classNames('bar', {
+              'active': index === store.data.indexA || index === store.data.indexB
+            })} style={{ height: item * 10 }}></div>
+          ))}
+        </div>
+
+        <button disabled={store.data.sorting} onClick={store.sort}>Start Bubble Sort</button>
+      </div>
+    )
+  }
+}
+
+render(<my-element />, 'body', new Store)
\ No newline at end of file
diff --git a/packages/playground/index.html b/packages/playground/index.html
index 4654437a1c..2470eb5bae 100644
--- a/packages/playground/index.html
+++ b/packages/playground/index.html
@@ -117,7 +117,8 @@
             <li class="button" data-example="hello-omi">Hello OMI</li>
             <li class="button" data-example="slot">Slot</li>
             <li class="button" data-example="fragment">Fragment</li>
-            <li class="button" data-example="unsafe-html">UnsafeHTML</li>
+            <li class="button" data-example="unsafe-html">Unsafe HTML</li>
+            <li class="button" data-example="bubble-sort">Bubble Sort</li>
             <!--
                 <li class="button" data-example="async-generators">
                 	Async generators
diff --git a/packages/playground/preview.html b/packages/playground/preview.html
index 1dc2936c2f..089fb2553c 100644
--- a/packages/playground/preview.html
+++ b/packages/playground/preview.html
@@ -32,6 +32,7 @@
     var render = Omi.render;
     var h = Omi.h;
     var tag = Omi.tag;
+    var classNames = Omi.classNames;
     // 不生效， 所以设置一下 React
     // jsxFragment: 'h.f',
     // jsxFragmentFactory: 'h.f',