Named Route Parameters

The :thingId Lane

Sometimes we don’t just want any thing, we want a specific thing. Route parameters are named URL segments that are used to capture the values specified at their position in the URL. We flag them with a colon (:).

Fig 1: The Designated Lane.

This allows us to create dynamic routes. Instead of hardcoding /users/1, /users/2, /users/3, we create one lane that handles them all.

// Route path: /things/:thingId
// Request URL: http://localhost:3000/things/42
app.get('/things/:thingId', (req, res) => {
  // Access the param via req.params
  console.log(req.params); // { thingId: '42' }

  res.send(`Details for thing #${req.params.thingId}`);
});

The captured values are populated in the req.params object. It’s like an designated lane pass — it lets specific traffic through based on ID.

Multiple Parameters

We can have multiple segments in a single route.

// Route path: /flights/:from/:to
// Request URL: http://localhost:3000/flights/YVR/LAX
app.get('/flights/:from/:to', (req, res) => {
  const { from, to } = req.params;
  res.send(`Flying from ${from} to ${to}`);
});

Professor Solo’s Directive: Parameter names are case-sensitive and must be made up of word characters ([A-Za-z0-9_]). Don’t get cute with emojis in variable names.

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Extra Bits & Bytes

Express Named Route Parameters - Demo Repo

Express Route Parameters

⏭ The Trunk

We’ve got the destination. Now where do we put the extra luggage? Let’s check the trunk (Query Strings).