expressjs.com/th/guide/debugging.md

---
layout: page
title: Debugging Express
menu: guide
lang: th
description: Learn how to enable and use debugging logs in Express.js applications
  by setting the DEBUG environment variable for enhanced troubleshooting.
---
# Debugging Express

To see all the internal logs used in Express, set the `DEBUG` environment variable to
`express:*` when launching your app.

```bash
$ DEBUG=express:* node index.js
```

On Windows, use the corresponding command.

```bash
> set DEBUG=express:* & node index.js
```

Running this command on the default app generated by the [express generator](/{{ page.lang }}/starter/generator.html) prints the following output:

```bash
$ DEBUG=express:* node ./bin/www
  express:router:route new / +0ms
  express:router:layer new / +1ms
  express:router:route get / +1ms
  express:router:layer new / +0ms
  express:router:route new / +1ms
  express:router:layer new / +0ms
  express:router:route get / +0ms
  express:router:layer new / +0ms
  express:application compile etag weak +1ms
  express:application compile query parser extended +0ms
  express:application compile trust proxy false +0ms
  express:application booting in development mode +1ms
  express:router use / query +0ms
  express:router:layer new / +0ms
  express:router use / expressInit +0ms
  express:router:layer new / +0ms
  express:router use / favicon +1ms
  express:router:layer new / +0ms
  express:router use / logger +0ms
  express:router:layer new / +0ms
  express:router use / jsonParser +0ms
  express:router:layer new / +1ms
  express:router use / urlencodedParser +0ms
  express:router:layer new / +0ms
  express:router use / cookieParser +0ms
  express:router:layer new / +0ms
  express:router use / stylus +90ms
  express:router:layer new / +0ms
  express:router use / serveStatic +0ms
  express:router:layer new / +0ms
  express:router use / router +0ms
  express:router:layer new / +1ms
  express:router use /users router +0ms
  express:router:layer new /users +0ms
  express:router use / <anonymous> +0ms
  express:router:layer new / +0ms
  express:router use / <anonymous> +0ms
  express:router:layer new / +0ms
  express:router use / <anonymous> +0ms
  express:router:layer new / +0ms
```

When a request is then made to the app, you will see the logs specified in the Express code:

```bash
  express:router dispatching GET / +4h
  express:router query  : / +2ms
  express:router expressInit  : / +0ms
  express:router favicon  : / +0ms
  express:router logger  : / +1ms
  express:router jsonParser  : / +0ms
  express:router urlencodedParser  : / +1ms
  express:router cookieParser  : / +0ms
  express:router stylus  : / +0ms
  express:router serveStatic  : / +2ms
  express:router router  : / +2ms
  express:router dispatching GET / +1ms
  express:view lookup "index.pug" +338ms
  express:view stat "/projects/example/views/index.pug" +0ms
  express:view render "/projects/example/views/index.pug" +1ms
```

To see the logs only from the router implementation set the value of `DEBUG` to `express:router`. Likewise, to see logs only from the application implementation set the value of `DEBUG` to `express:application`, and so on.

## Applications generated by `express`

An application generated by the `express` command uses the `debug` module and its debug namespace is scoped to the name of the application.

For example, if you generated the app with `$ express sample-app`, you can enable the debug statements with the following command:

```bash
$ DEBUG=sample-app:* node ./bin/www
```

You can specify more than one debug namespace by assigning a comma-separated list of names:

```bash
$ DEBUG=http,mail,express:* node index.js
```