---
order: 7
title:
zh-CN: 限制用户上传的文件
en-US: Filter uploads files
---
## zh-CN
可以通过 `beforeUpload` 在文件上传之前进行干预，如限制用户只能上传 JPG 文件。
也支持异步检查，`beforeUpload` 的返回值可以是一个 Promise：[示例](http://react-component.github.io/upload/examples/beforeUpload.html)。
## en-US
You can use `beforeUpload` to check whether user can upload, for example, limit file type only to be JPG. Checking can also be asynchronous. The return value can also be a Promise for function `beforeUpload`
````jsx
import { Upload, Button, Icon, message } from 'antd';
const props = {
action: '/upload.do',
beforeUpload(file) {
const isJPG = file.type === 'image/jpeg';
if (!isJPG) {
message.error('you can only upload JPG file~');
}
return isJPG;
},
};
ReactDOM.render(
< Upload { . . . props } >
< Button type = "ghost" >
< Icon type = "upload" / > upload
< / Button >
< / Upload >
, mountNode);
````
