[Improvement] Button: add square prop (#1627)

packages/button/en-US.md

@@ -71,6 +71,7 @@ Use `tag` prop to custom button tag
 | disabled | Whether to disable button | `Boolean` | `false` |
 | loading | Whether show loading status | `Boolean` | `false` |
 | block | Whether to set display block | `Boolean` | `false` |
+| square | Whether to be square button | `Boolean` | `false` |
 
 ### Event
 

packages/button/index.vue

@@ -9,6 +9,7 @@
       {
         block,
         plain,
+        square,
         loading,
         disabled,
         unclickable: disabled || loading,
@@ -34,6 +35,7 @@ export default create({
     text: String,
     block: Boolean,
     plain: Boolean,
+    square: Boolean,
     loading: Boolean,
     disabled: Boolean,
     nativeType: String,

packages/button/zh-CN.md

@@ -76,6 +76,7 @@ Vue.use(Button);
 | disabled | 是否禁用 | `Boolean` | `false` |
 | loading | 是否显示为加载状态 | `Boolean` | `false` |
 | block | 是否为块级元素 | `Boolean` | `false` |
+| square | 是否为方形按钮 | `Boolean` | `false` |
 
 ### Event
 

packages/vant-css/src/button.css

@@ -143,4 +143,8 @@
     background-color: $button-disabled-background-color;
     border: 1px solid $button-disabled-border-color;
   }
+
+  &--square {
+    border-radius: 0;
+  }
 }