Node.js doesn't handle an error in express

Question

I have a simple server:

const express = require("express");
const app = express();

var meetings = [];

app.use("/static", express.static("public/"))
app.use("/index.html?", function(request, response, next) {
    response.redirect("/");
})

app.get("/", function(request, response) {
    response.sendFile(__dirname + "/pages/index.html");
})

try {
    app.listen(80);
} catch(e) {
    console.log("Can't run on port 80. Please, run me as a sudo!");
}

When I run it, I got EACCES error.

How to handle an exception? Any help is appreciated.

You can’t listen on a port below 1024 without being root - they are historically “privileged ports”. — Joe, Nov 11 '21 at 12:12
Does this answer your question? [Node.js app can't run on port 80 even though there's no other process blocking the port](https://stackoverflow.com/questions/18947356/node-js-app-cant-run-on-port-80-even-though-theres-no-other-process-blocking-t) — Joe, Nov 11 '21 at 12:13

score 2 · Accepted Answer · answered Nov 11 '21 at 14:22

I think you can't catch it like that because app.listen() always return a <net.Server> instance. To catch an error on this instance you should look for the error event. So, this is how you would catch it.

const express = require("express");
const app = express();

var meetings = [];

app.use("/static", express.static("public/"))
app.use("/index.html?", function(request, response, next) {
    response.redirect("/");
})

app.get("/", function(request, response) {
    response.sendFile(__dirname + "/pages/index.html");
})


app.listen(80).on(error => { 
  if (error.code === "EACCESS") {
    console.log("Can't run on port 80. Please, run me as a sudo!");
  }
});

As for why it can't find express, is that I am guessing if you run it with sudo, it looks for globally installed modules. But this is just a guess because it runs fine when I run the same code with sudo on my machine.

Node.js doesn't handle an error in express

1 Answers1