定义async uni.chooseImage函数时报错，提示 unexpected token

代码如下
<script>

//前端代码
async uni.chooseImage({
count: 1,
success(res) {
console.log(res);
if (res.tempFilePaths.length > 0) {
let filePath = res.tempFilePaths[0]
//进行上传操作

        // promise方式  
        const result = await uniCloud.uploadFile({  
            filePath: filePath,  
    cloudPath: 'a.jpg',  
            onUploadProgress: function(progressEvent) {  
                  console.log(progressEvent);  
                  var percentCompleted = Math.round(  
                    (progressEvent.loaded * 100) / progressEvent.total  
                  );  
                }  
        });  

        // callback方式，与promise方式二选一即可  
        uniCloud.uploadFile({  
            filePath: filePath,  
    cloudPath: 'a.jpg',  
    onUploadProgress: function(progressEvent) {  
      console.log(progressEvent);  
      var percentCompleted = Math.round(  
        (progressEvent.loaded * 100) / progressEvent.total  
      );  
            },  
            success() {},  
            fail() {},  
            complete() {}  
        });  

    }  
}  

});
</script>

求大佬指导