怎么写一个 Vite 插件 ​

// vite-plugin-demo.ts
import { Plugin } from "vite";

export default function viteDemo(): Plugin {
  return {
    name: "vite:demo",
    config(config) {
      return {
        server: {
          port: config.server?.port || 3456,
        },
      };
    },
    configResolved(resConfig) {
      console.log("vite-demo-resolved: ", resConfig.server);
    },
  };
}
// 用法 vite.config.ts
import { defineConfig } from "vite";
import vue from "@vitejs/plugin-vue";
import viteDemoPlugin from "./src/plugins/vite-plugin-demo";

export default defineConfig({
  plugins: [vue(), viteDemoPlugin()],
  server: {
    port: 3062,
  },
});