debug

# debug
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<img width="647" src="https://user-images.githubusercontent.com/71256/29091486-fa38524c-7c37-11e7-895f-e7ec8e1039b6.png">

A tiny JavaScript debugging utility modelled after Node.js core's debugging
technique. Works in Node.js and web browsers.

## Installation

```bash
$ npm install debug
```

## Usage

`debug` exposes a function; simply pass this function the name of your module, and it will return a decorated version of `console.error` for you to pass debug statements to. This will allow you to toggle the debug output for different parts of your module as well as the module as a whole.

Example _app.js_:

```js
var debug = require('debug')('http')
  , http = require('http')
  , name = 'My App';

// fake app

debug('booting %o', name);

http.createServer(function(req, res){
  debug(req.method + ' ' + req.url);
  res.end('hello\n');
}).listen(3000, function(){
  debug('listening');
});

// fake worker of some kind

require('./worker');
```

Example _worker.js_:

```js
var a = require('debug')('worker:a')
  , b = require('debug')('worker:b');

function work() {
  a('doing lots of uninteresting work');
  setTimeout(work, Math.random() * 1000);
}

work();

function workb() {
  b('doing some work');
  setTimeout(workb, Math.random() * 2000);
}

workb();
```

The `DEBUG` environment variable is then used to enable these based on space or
comma-delimited names.

Here are some examples:

<img width="647" alt="screen shot 2017-08-08 at 12 53 04 pm" src="https://user-images.githubusercontent.com/71256/29091703-a6302cdc-7c38-11e7-8304-7c0b3bc600cd.png">
<img width="647" alt="screen shot 2017-08-08 at 12 53 38 pm" src="https://user-images.githubusercontent.com/71256/29091700-a62a6888-7c38-11e7-800b-db911291ca2b.png">
<img width="647" alt="screen shot 2017-08-08 at 12 53 25 pm" src="https://user-images.githubusercontent.com/71256/29091701-a62ea114-7c38-11e7-826a-2692bedca740.png">

#### Windows command prompt notes

##### CMD

On Windows the environment variable is set using the `set` command.

```cmd
set DEBUG=*,-not_this
```

Example:

```cmd
set DEBUG=* & node app.js
```

##### PowerShell (VS Code default)

PowerShell uses different syntax to set environment variables.

```cmd
$env:DEBUG = "*,-not_this"
```

Example:

```cmd
$env:DEBUG='app';node app.js
```

Then, run the program to be debugged as usual.

npm script example:
```js
  "windowsDebug": "@powershell -Command $env:DEBUG='*';node app.js",
```

## Namespace Colors

Every debug instance has a color generated for it based on its namespace name.
This helps when visually parsing the debug output to identify which debug instance
a debug line belongs to.

#### Node.js

In Node.js, colors are enabled when stderr is a TTY. You also _should_ install
the [`supports-color`](https://npmjs.org/supports-color) module alongside debug,
oth