feat(Button): add class-prefix prop to support custom icon (#3159)

packages/button/README.md

@@ -120,6 +120,7 @@
 | size | 按钮尺寸，可选值为 `normal` `large` `small` `mini` | _string_ | `normal` | - |
 | color | 按钮颜色，支持传入`linear-gradient`渐变色 | _string_ | - | 1.0.0 |
 | icon | 左侧图标名称或图片链接，可选值见 [Icon 组件](#/icon) | _string_ | - | - |
+| class-prefix | 类名前缀 用法等同于[Icon 组件](#/icon) | _string_ | `van-icon` | - |
 | plain | 是否为朴素按钮 | _boolean_ | `false` | - |
 | block | 是否为块级元素 | _boolean_ | `false` | - |
 | round | 是否为圆形按钮 | _boolean_ | `false` | - |

packages/button/index.ts

@@ -13,6 +13,10 @@ VantComponent({
 
   props: {
     icon: String,
+    classPrefix: {
+      type: String,
+      value: 'van-icon',
+    },
     plain: Boolean,
     block: Boolean,
     round: Boolean,
@@ -73,7 +77,7 @@ VantComponent({
         this.$emit('click');
       }
     },
-
+    
     noop() {},
   },
 });

packages/button/index.wxml

@@ -31,10 +31,7 @@
       type="{{ loadingType }}"
       color="{{ loadingColor(type,color,plain) }}"
     />
-    <view
+    <view wx:if="{{ loadingText }}" class="van-button__loading-text">
-      wx:if="{{ loadingText }}"
-      class="van-button__loading-text"
-    >
       {{ loadingText }}
     </view>
   </block>
@@ -43,6 +40,7 @@
       wx:if="{{ icon }}"
       size="1.2em"
       name="{{ icon }}"
+      class-prefix="{{classPrefix}}"
       class="van-button__icon"
       custom-style="line-height: inherit;"
     />