mixins/index.js文件

export default {
  methods: {
    sayHello() {
      alert("hello");
    }
  }
};

在使用的页面引入

<script>
import commont from "./mixins/index.js";//引入混入
import { getCurrentInstance, onMounted } from "vue";
export default {
  name: "App",
  mixins: [commont ],//使用混入
  setup() {
    const { proxy } = getCurrentInstance();
    onMounted(() => {
      proxy.sayHello();
    });
  },
};
</script>