import/export in Typescript - visual-studio

Question

I have an existing Node.js (Node only, no Typescript) application with the following files (generated by Visual Studio Node template):
In file app.js:
var express = require("express");
var app = express();
...
module.exports = app;
In file socket.js:
module.exports = function (server,app) {
// ....
}
In file www:
var app = require("../app");
var server = app.listen(app.get(8081), function() {
});
var sockets = require("../routes/sockets")(server, app);
I am no migrating it to Typescript. How do I convert the above export/require to the equivalent in Typescript?
Where can I find the proper specifications of the import and export keywords? I am unable to find documentation of what they mean and do exactly. I do see many examples of some permutations of their usage.

Answer 1

To ensure that your import statements will be transpiled into require(), you need to specify that you want to use commonjs modules during the TypeScript compilation. Here's an example of tsconfig.json:
{
"compilerOptions": {
"module": "commonjs",
"outDir": "build",
"target": "es5"
}
}
Here's an example of the Node/Express server in TypeScript:
import * as express from "express";
const app = express();
app.get('/products', (req, res) => res.send('Got a request for products'));
const server = app.listen(8000, "localhost", () => {
const {address, port} = server.address();
console.log('Listening on %s %s', address, port);
});