diff --git a/example/app.json b/example/app.json
index 588e5965..2f0f8b74 100644
--- a/example/app.json
+++ b/example/app.json
@@ -36,6 +36,5 @@
     "navigationBarTextStyle": "black",
     "backgroundTextStyle": "dark",
     "backgroundColor": "#f8f8f8"
-  },
-  "debug": true
+  }
 }
diff --git a/example/pages/button/index.wxml b/example/pages/button/index.wxml
index 9d4f8352..a47ef526 100644
--- a/example/pages/button/index.wxml
+++ b/example/pages/button/index.wxml
@@ -1,7 +1,7 @@
 <demo-section>
   <demo-block title="按钮类型" padding>
     <view class="row">
-      <van-button type="default" custom-class="demo-margin-right">默认按钮</van-button>
+      <van-button custom-class="demo-margin-right">默认按钮</van-button>
       <van-button type="primary">主要按钮</van-button>
     </view>
     <van-button type="warning" custom-class="demo-margin-right">警告按钮</van-button>
@@ -10,7 +10,7 @@
 
   <demo-block title="朴素按钮" padding>
     <view class="row">
-      <van-button type="default" plain custom-class="demo-margin-right">默认按钮</van-button>
+      <van-button plain custom-class="demo-margin-right">默认按钮</van-button>
       <van-button type="primary" plain>主要按钮</van-button>
     </view>
     <van-button type="warning" plain custom-class="demo-margin-right">警告按钮</van-button>
@@ -19,7 +19,7 @@
 
   <demo-block title="按钮尺寸" padding>
     <van-button size="large" block custom-class="demo-margin-bottom">大号按钮</van-button>
-    <van-button size="normal" class="demo-margin-right">普通按钮</van-button>
+    <van-button class="demo-margin-right">普通按钮</van-button>
     <van-button size="small" class="demo-margin-right">小型按钮</van-button>
     <van-button size="mini">迷你按钮</van-button>
   </demo-block>
diff --git a/packages/button/index.js b/packages/button/index.js
index 6596c4a3..a7f0a165 100644
--- a/packages/button/index.js
+++ b/packages/button/index.js
@@ -1,35 +1,37 @@
 import { create } from '../common/create';
-import { classNames } from '../common/class-names';
 import { button } from '../mixins/button';
 
-const booleanProp = {
-  type: Boolean,
-  observer: 'setClasses'
-};
-
 create({
   mixins: [button],
 
   props: {
+    plain: Boolean,
+    block: Boolean,
+    square: Boolean,
+    loading: Boolean,
+    disabled: Boolean,
     type: {
       type: String,
-      value: 'default',
-      observer: 'setClasses'
+      value: 'default'
     },
     size: {
       type: String,
-      value: 'normal',
-      observer: 'setClasses'
-    },
-    plain: booleanProp,
-    block: booleanProp,
-    square: booleanProp,
-    loading: booleanProp,
-    disabled: booleanProp
+      value: 'normal'
+    }
   },
 
-  attached() {
-    this.setClasses();
+  computed: {
+    classes() {
+      const { type, size, plain, disabled, loading, square, block } = this.data;
+      return this.classNames(`van-button--${type}`, `van-button--${size}`, {
+        'van-button--block': block,
+        'van-button--plain': plain,
+        'van-button--square': square,
+        'van-button--loading': loading,
+        'van-button--disabled': disabled,
+        'van-button--unclickable': disabled || loading
+      });
+    }
   },
 
   methods: {
@@ -37,20 +39,6 @@ create({
       if (!this.data.disabled && !this.data.loading) {
         this.$emit('click');
       }
-    },
-
-    setClasses() {
-      const { type, size, plain, disabled, loading, square, block } = this.data;
-      this.setData({
-        classes: classNames(`van-button--${type}`, `van-button--${size}`, {
-          'van-button--block': block,
-          'van-button--plain': plain,
-          'van-button--square': square,
-          'van-button--loading': loading,
-          'van-button--disabled': disabled,
-          'van-button--unclickable': disabled || loading
-        })
-      });
     }
   }
 });
diff --git a/packages/common/create.js b/packages/common/create.js
index a6174a82..6d76447b 100644
--- a/packages/common/create.js
+++ b/packages/common/create.js
@@ -1,4 +1,5 @@
 import { basic } from '../mixins/basic';
+import { observe } from '../mixins/observer/index';
 
 export function create(sfc) {
   // map props to properties
@@ -34,5 +35,6 @@ export function create(sfc) {
     sfc.behaviors.push('wx://form-field');
   }
 
+  observe(sfc);
   Component(sfc);
 };
diff --git a/packages/mixins/basic.js b/packages/mixins/basic.js
index b6532124..bad37d45 100644
--- a/packages/mixins/basic.js
+++ b/packages/mixins/basic.js
@@ -1,5 +1,9 @@
+import { classNames } from '../common/class-names';
+
 export const basic = Behavior({
   methods: {
+    classNames,
+
     $emit() {
       this.triggerEvent.apply(this, arguments);
     },
diff --git a/packages/mixins/observer/behavior.js b/packages/mixins/observer/behavior.js
new file mode 100644
index 00000000..47e988c3
--- /dev/null
+++ b/packages/mixins/observer/behavior.js
@@ -0,0 +1,34 @@
+export const behavior = Behavior({
+  created() {
+    if (!this.$options) {
+      return;
+    }
+
+    const cache = {};
+    const { setData } = this;
+    const { computed } = this.$options();
+    const keys = Object.keys(computed);
+
+    const calcComputed = () => {
+      const needUpdate = {};
+      keys.forEach(key => {
+        const value = computed[key].call(this);
+
+        if (cache[key] !== value) {
+          cache[key] = needUpdate[key] = value;
+        }
+      });
+
+      return needUpdate;
+    };
+
+    this.setData = (data, callback) => {
+      data && setData.call(this, data, callback);
+      setData.call(this, calcComputed());
+    };
+  },
+
+  attached() {
+    this.setData();
+  }
+});
diff --git a/packages/mixins/observer/index.js b/packages/mixins/observer/index.js
new file mode 100644
index 00000000..0cba0aec
--- /dev/null
+++ b/packages/mixins/observer/index.js
@@ -0,0 +1,14 @@
+import { behavior } from './behavior';
+import { observeProps } from './props';
+
+export function observe(sfc) {
+  if (sfc.computed) {
+    sfc.behaviors.push(behavior);
+    sfc.methods = sfc.methods || {};
+    sfc.methods.$options = () => sfc;
+
+    if (sfc.properties) {
+      observeProps(sfc.properties);
+    }
+  }
+}
diff --git a/packages/mixins/observer/props.js b/packages/mixins/observer/props.js
new file mode 100644
index 00000000..98871de1
--- /dev/null
+++ b/packages/mixins/observer/props.js
@@ -0,0 +1,25 @@
+export function observeProps(props) {
+  if (!props) {
+    return;
+  }
+
+  Object.keys(props).forEach(key => {
+    let prop = props[key];
+    if (!prop.type) {
+      prop = { type: prop };
+    }
+
+    let { observer } = prop;
+    prop.observer = function() {
+      if (observer) {
+        if (typeof observer === 'string') {
+          observer = this[observer];
+        }
+        observer.apply(this, arguments);
+      }
+      this.setData();
+    };
+
+    props[key] = prop;
+  });
+}