Layout: optimize doc && code review

packages/row/src/row.vue

@@ -1,32 +1,31 @@
 <template>
-  <div
-    :class="`${prefix}-row`"
-    :style="style">
+  <div :class="`${prefix}-row`" :style="style">
     <slot></slot>
   </div>
 </template>
 
 <script>
-  export default {
-    name: 'van-row',
-    props: {
-      prefix: {
-        type: String,
-        default: 'van'
-      },
-      gutter: {
-        type: [Number, String],
-        default: 0
-      }
+export default {
+  name: 'van-row',
+
+  props: {
+    prefix: {
+      type: String,
+      default: 'van'
     },
-    computed: {
-      style() {
-        const gutter = Number(this.gutter);
-        const margin = `-${gutter / 2}px`;
-        return gutter
-          ? { marginLeft: margin, marginRight: margin }
-          : {};
-      }
+    gutter: {
+      type: [Number, String],
+      default: 0
     }
-  };
+  },
+
+  computed: {
+    style() {
+      const margin = `-${Number(this.gutter) / 2}px`;
+      return this.gutter
+        ? { marginLeft: margin, marginRight: margin }
+        : null;
+    }
+  }
+};
 </script>