tiny node.js debugging utility modelled after node core's debugging technique.
## Installation
```bash
$ npm install debug
```
## Usage
With `debug` you simply invoke the exported function to generate your debug function, passing it a name which will determine if a noop function is returned, or a decorated `console.error`, so all of the `console` format string goodies you're used to work fine. A unique color is selected per-function for visibility.
Example _app.js_:
```js
var debug = require('debug')('http')
, http = require('http')
, name = 'My App';
// fake app
debug('booting %s', 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 debug = require('debug')('worker');
setInterval(function(){
debug('doing some work');
}, 1000);
```
The __DEBUG__ environment variable is then used to enable these based on space or comma-delimited names. Here are some examples:
When actively developing an application it can be useful to see when the time spent between one `debug()` call and the next. Suppose for example you invoke `debug()` before requesting a resource, and after as well, the "+NNNms" will show you how much time was spent between calls.
If you're using this in one or more of your libraries, you _should_ use the name of your library so that developers may toggle debugging as desired without guessing names. If you have more than one debuggers you _should_ prefix them with your library name and use ":" to separate features. For example "bodyParser" from Connect would then be "connect:bodyParser".
The `*` character may be used as a wildcard. Suppose for example your library has debuggers named "connect:bodyParser", "connect:compress", "connect:session", instead of listing all three with `DEBUG=connect:bodyParser,connect:compress,connect:session`, you may simply do `DEBUG=connect:*`, or to run everything using this module simply use `DEBUG=*`.
You can also exclude specific debuggers by prefixing them with a "-" character. For example, `DEBUG=*,-connect:*` would include all debuggers except those starting with "connect:".
## Browser support
Debug works in the browser as well, currently persisted by `localStorage`. Consider the situation shown below where you have `worker:a` and `worker:b`, and wish to debug both. Somewhere in the code on your page, include:
```js
window.myDebug = require("debug");
```
("debug" is a global object in the browser so we give this object a different name.) When your page is open in the browser, type the following in the console:
```js
myDebug.enable("worker:*")
```
Refresh the page. Debug output will continue to be sent to the console until it is disabled by typing `myDebug.disable()` in the console.
```js
a = debug('worker:a');
b = debug('worker:b');
setInterval(function(){
a('doing some work');
}, 1000);
setInterval(function(){
b('doing some work');
}, 1200);
```
#### Web Inspector Colors
Colors are also enabled on "Web Inspectors" that understand the `%c` formatting
option. These are WebKit web inspectors, Firefox ([since version
