Middleware
Intercept request, response and errors using H3 middleware.
We recommend using composable utilities whenever possible. Global middleware can complicate application logic, making it less predictable and harder to understand.
Global middleware run on each request before route handler and act as wrappers to intercept request, response and errors.
You can register global middleware to app instance using the H3.use.
Example: Register a global middleware that logs every request.
app.use((event) => {
console.log(event);
});
Example: Register a global middleware that matches certain requests.
app.use(
"/blog/**",
(event, next) => {
console.log("[alert] POST request on /blog paths!");
},
{
method: "POST",
// match: (event) => event.req.method === "POST",
},
);
You can register middleware with next argument to intercept return values of next middleware and handler.
app.use(async (event, next) => {
const rawBody = await next();
// [intercept response]
return rawBody;
});
Example below, always responsds with Middleware 1.
app
.use(() => "Middleware 1")
.use(() => "Middleware 2")
.get("/", "Hello");
If middleware returns a value other than
undefined or the result of next(), it immediately intercepts request handling and sends a response.When adding routes, you can register middleware that only run with them.
import { basicAuth } from "h3";
app.get(
"/secret",
(event) => {
/* ... */
},
{
middleware: [basicAuth({ password: "test" })],
},
);
For convenience, H3 provides middleware factory functions onRequest, onResponse, and onError:
import { onRequest, onResponse, onError } from "h3";
app.use(
onRequest((event) => {
console.log(`[${event.req.method}] ${event.url.pathname}`);
}),
);
app.use(
onResponse((response, event) => {
console.log(`[${event.req.method}] ${event.url.pathname} ~>`, body);
}),
);
app.use(
onError((error, event) => {
console.log(
`[${event.req.method}] ${event.url.pathname} !! ${error.message}`,
);
}),
);