react中setStatus怎么对obj对象进行修改

this.state = {
       // 上传图片信息
      imageObj:{
        name:'',
        time:'',
        size:'',
        base64:''
      }
 }

通过拷贝的方法实现Object.assign
let imageObj = Object.assign({}, this.state.imageObj, { 
  name: file.name,
  time: '',
  size: file.size,
  base64: reader.result 
});
this.setState({
  imageObj: imageObj
});