avatar img add "alt" prop (#10798)

components/avatar/index.en-US.md

@@ -14,3 +14,4 @@ Avatars can be used to represent people or objects. It supports images, `Icon`s,
 | shape | the shape of avatar | `circle` \| `square` | `circle` |
 | size | the size of the avatar | `large` \| `small` \| `default` | `default` |
 | src | the address of the image for an image avatar | string | - |
+| alt | This attribute defines the alternative text describing the image | string | - |

components/avatar/index.tsx

@@ -16,6 +16,7 @@ export interface AvatarProps {
   prefixCls?: string;
   className?: string;
   children?: any;
+  alt?: string;
 }
 
 export interface AvatarState {
@@ -75,7 +76,7 @@ export default class Avatar extends React.Component<AvatarProps, AvatarState> {
 
   render() {
     const {
-      prefixCls, shape, size, src, icon, className, ...others
+      prefixCls, shape, size, src, icon, className, alt, ...others
     } = this.props;
 
     const sizeCls = classNames({
@@ -95,6 +96,7 @@ export default class Avatar extends React.Component<AvatarProps, AvatarState> {
         <img
           src={src}
           onError={this.handleImgLoadError}
+          alt={alt}
         />
       );
     } else if (icon) {

components/avatar/index.zh-CN.md

@@ -15,3 +15,4 @@ title: Avatar
 | shape | 指定头像的形状 | Enum{ 'circle', 'square' } | `circle` |
 | size | 设置头像的大小 | Enum{ 'large', 'small', 'default' } | `default` |
 | src | 图片类头像的资源地址 | string | - |
+| alt | 图像无法显示时的替代文本 | string | - |