為什么我這個vue代碼里的watch(偵聽器)不起作用?

  import axios from 'axios';

  export default {
    name: 'Search',
    props: {
      requireType: {
        type: String,
        required: true,
      },
    },
    data() {
      return {
        searchModal: {
          select: 'weibo',
          value: '',
        },
        require: this.requireType,
      };
    },
    methods: {
      search() {
        if (this.require === 'focused') {
          axios.get('./static/hotRadeFocused.json')
            .then((response) => {
              this.$emit('getData', response.data);
            });
        }
        if (this.require === 'weibo') {
          axios.get('./static/hotRadeWeibo.json')
            .then((response) => {
              this.$emit('getData', response.data);
            });
        }
      },
    },
    watch: {
      require: function (val) {
        this.search();
      },
    },
    beforeMount() {
      this.search();
    },
  };