Plugins
H3 plugins allow you to extend an H3 app instance with reusable logic.
Register Plugins
Plugins can be registered either when creating a new H3 instance or by using H3.register.
import { H3 } from "h3";
import { logger } from "./logger.mjs";
// Using instance config
const app = new H3({
plugins: [logger()],
});
// Or register later
app.register(logger());
// ... rest of the code..
app.get("/**", () => "Hello, World!");
Plugins are always registered immediately. Therefore, the order in which they are used might be important depending on the plugin's functionality.
Creating Plugins
H3 plugins are simply functions that accept an H3 instance as the first argument and immediately apply logic to extend it.
app.register((app) => {
app.use(...)
})
For convenience, H3 provides a built-in definePlugin utility, which creates a typed factory function with optional plugin-specific options.
import { definePlugin } from "h3";
const logger = definePlugin((h3, _options) => {
if (h3.config.debug) {
h3.use((req) => {
console.log(`[${req.method}] ${req.url}`);
});
}
});