Route Order Matters

Express tries routes in the order you declared them. Specific before general.

3 min read Level 2/5 #express#routing#order

What you'll learn

Order routes from specific to general
Recognize the common bug
Use rote ordering for middleware too

Express matches routes in declaration order. The first one that matches wins.

The Classic Bug

app.get("/users/:id", getUserById);
app.get("/users/me",   getCurrentUser);

What happens when you hit GET /users/me?

:id matches me. getUserById runs with req.params.id === "me". getCurrentUser never runs.

The Fix — Specific Before General

app.get("/users/me",   getCurrentUser);   // specific first
app.get("/users/:id",  getUserById);      // catch-all after

Rule of thumb: literal paths before parameter paths.

Multiple Params

app.get("/users/:id/edit", editForm);     // ok
app.get("/users/:id",      showUser);      // ok — different path lengths

Different path lengths can’t clash. The conflict is only when the length matches.

Middleware Order

The same rule applies to middleware mounted with app.use():

app.use(logger);            // 1st — runs for every request
app.use(express.json());    // 2nd — parses body
app.use("/api", apiAuth);   // 3rd — only on /api/*
app.use("/api", apiRouter); // 4th — actual API routes
app.use(errorHandler);      // last — catches errors

A request flows top to bottom until something responds.

Error Middleware Goes LAST

app.use(routes);
app.use((err, req, res, next) => { /* ... */ });   // ← always last

Express only directs errors to middleware that has 4 args, but it won’t reach them if earlier middleware swallowed the request.

Avoiding Order Hell

When a route file is long, group by URL prefix and order within each group from specific to general. Keep the file scannable and order issues stay rare.

`app.param()` →