Express.js

Updated: 2021-11-19

Route

In app.js

var routes = require("./routes");

app.get("/loadData/:name", routes.loadData);

In routes/index.js

exports.loadData = function (req, res) {
  console.log(req.route.params.name);
  // or
  console.log(req.params.name);
};

In browser

http://127.0.0.1:3000/loaddata/foo

In terminal

foo

Enable CORS

If you see error like:

XMLHttpRequest cannot load <some_url>. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '<origin_url>' is therefore not allowed access.

Add the followings to the app.js:

app.all("*", function (req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Headers", "X-Requested-With");
  next();
});

Req Lookup

Params

In Express 4:

Params are stored as

req.params.<param_name>

E.g. in app.js:

app.get('/foo/:name', ...)

A request to /foo/bar will generate

req.params.name == "bar";

File Upload

Uploaded files

req.files.<file_name>.path

Data Upload

Uploaded data

req.body.<data_name>

req.files and req.body are available for POST requests, but not GET requests

Serve Route Based on File Structure

To serve multi-player routes and map to files in arbitrary folder hierarchy, e.g.

http://www.example.com/page/a to partial/a.html
http://www.example.com/page/b/c to partial/b/c.html
http://www.example.com/page/d/e/f to partial/d/e/f.html

app.route("/page/:name").get(function (req, res) {
  res.render("partials/" + req.params.name);
});

Multer

File Upload

https://github.com/expressjs/multer

Auto reload in development

Use Automon:

$ npm install -g nodemon

Then use nodemon instead of node when starting the app:

$ nodemon app.js