The data property “article” is already declared as a prop. Use prop default value instead

You have added article at both places data and props. It should be one of these, thats why you are getting the error. You have to remove it one of the place, if you are passing it from parent component, then keep it as props. If this is a local instance data, keep it in vue data block.

export default {
  props: {
    article: {
      type: Object
    }
  },
  data() {
    return {
      article: this.article
    }
  },
  methods: {
    itemClick() {
      console.log('itemClick');
    }
  }
};