vue2子组件改父组件值

适用于子组件单纯想修改父组件值的场景
1. this.$emit('change',value)
value是新值，传递给子组件

适用于子组件先展示父组件的值，并且想更改uploadInfo的场景，uploadInfo在父组件也会被响应到newUploadInfo的修改
  props: {
    uploadInfo: {
      type: Object,
      default: () => ({}),
    },
  },
  watch: {
    uploadInfo: {
      handler(value) {
        this.newUploadInfo =value;
      },
      immediate: true,
    },
  }

this.newUploadInfo.xxx=1
console.log(this.uploadInfo.xxx) 也是为1