# debug
[![Build Status](https://travis-ci.org/visionmedia/debug.svg?branch=master)](https://travis-ci.org/visionmedia/debug) [![Coverage Status](https://coveralls.io/repos/github/visionmedia/debug/badge.svg?branch=master)](https://coveralls.io/github/visionmedia/debug?branch=master) [![Slack](https://visionmedia-community-slackin.now.sh/badge.svg)](https://visionmedia-community-slackin.now.sh/) [![OpenCollective](https://opencollective.com/debug/backers/badge.svg)](#backers)
[![OpenCollective](https://opencollective.com/debug/sponsors/badge.svg)](#sponsors)
A tiny node.js debugging utility modelled after node core's debugging technique.
**Discussion around the V3 API is under way [here](https://github.com/visionmedia/debug/issues/370)**
## 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 %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:
![debug http and worker](http://f.cl.ly/items/18471z1H402O24072r1J/Screenshot.png)
![debug worker](http://f.cl.ly/items/1X413v1a3M0d3C2c1E0i/Screenshot.png)
#### Windows note
On Windows the environment variable is set using the `set` command.
```cmd
set DEBUG=*,-not_this
```
Note that PowerShell uses different syntax to set environment variables.
```cmd
$env:DEBUG = "*,-not_this"
```
Then, run the program to be debugged as usual.
## Millisecond diff
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.
![](http://f.cl.ly/items/2i3h1d3t121M2Z1A3Q0N/Screenshot.png)
When stdout is not a TTY, `Date#toUTCString()` is used, making it more useful for logging the debug information as shown below:
![](http://f.cl.ly/items/112H3i0e0o0P0a2Q2r11/Screenshot.png)
## Conventions
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".
## Wildcards
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:".
## Environment Variables
When running through Node.js, you can set a few environment variables that will
change the behavior of the debug logging:
| Name | Purpose |
|-----------|-------------------------------------------------|
| `DEBUG` | Enables/disabled specific debugging namespaces. |
| `DEBUG_COLORS`| Whether or not to use colors in the debug output. |
| `DEBUG_DEPTH` | Object inspection depth. |
| `DEBUG_SHOW_HIDDEN` | Shows hidden properties on inspected objects. |
__Note:__ The environment variables beginning with `DEBUG_` end up being
converted into an Options object that gets used with `%o`/`%O` formatters.
See the Node.js documentation for
[`util.inspect()`](https://nodejs.org/api/util.html#util_util_inspect_object_options)
for the complete list.
## Formatters
Debug uses [printf-style](https://wikipedia.org/wiki/Printf_format_string) formatting. Below are the officially supported formatters:
| Formatter | Representation |
|-----------|----------------|
| `%O` | Pretty-print an Object on multiple lines. |
| `%o` | Pretty-print an Object all on a single line. |
| `%s` | String. |
| `%d` | Number (both integer and float). |
| `%j` | JSON. Replaced with the string '[Circular]' if the argument contains circular references. |
| `%%` | Single percent sign ('%'). This does not consume an argument. |
### Custom formatters
You can add custom formatters by extending the `debug.formatters` object. For example, if you wanted to add support for rendering a Buffer as hex with `%h`, you could do something like:
```js
const createDebug = require('debug')
createDebug.formatters.h = (v) => {
return v.toString('hex')
}
// …elsewhere
const debug = createDebug('foo')
debug('this is hex: %h', new Buffer('hello world'))
// foo this is hex: 68656c6c6f20776f726c6421 +0ms
```
## Browser support
You can build a browser-ready script using [browserify](https://github.com/substack/node-browserify),
or just use the [browserify-as-a-service](https://wzrd.in/) [build](https://wzrd.in/standalone/debug@latest),
if you don't want to build it yourself.
Debug's enable state is currently persisted by `localStorage`.
Consider the situation shown below where you have `worker:a` and `worker:b`,
and wish to debug both. You can enable this using `localStorage.debug`:
```js
localStorage.debug = 'worker:*'
```
And then refresh the page.
```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
31](https://hacks.mozilla.org/2014/05/editable-box-model-multiple-selection-sublime-text-keys-much-more-firefox-developer-tools-episode-31/))
and the Firebug plugin for Firefox (any version).
Colored output looks something like:
![](https://cloud.githubusercontent.com/assets/71256/3139768/b98c5fd8-e8ef-11e3-862a-f7253b6f47c6.png)
## Output streams
By default `debug` will log to stderr, however this can be configured per-namespace by overriding the `log` method:
Example _stdout.js_:
```js
var debug = require('debug');
var error = debug('app:error');
// by default stderr is used
error('goes to stderr!');
var log = debug('app:log');
// set this namespace to log via console.log
log.log = console.log.bind(console); // don't forget to bind to console!
log('goes to stdout');
error('still goes to stderr!');
// set all output to go via console.info
// overrides all per-namespace log settings
debug.log = console.info.bind(console);
error('now goes to stdout via console.info');
log('still goes to stdout, but via console.info now');
```
## Authors
- TJ Holowaychuk
- Nathan Rajlich
- Andrew Rhyne
## Backers
Support us with a monthly donation and help us continue our activities. [[Become a backer](https://opencollective.com/debug#backer)]
<a href="https://opencollective.com/debug/backer/0/website" target="_blank"><img src="https://opencollective.com/debug/backer/0/avatar.svg"></a>
<a href="https://opencollective.com/debug/backer/1/website" targ
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HTML5调用摄像头+视频特效+录制视频+录音+截图+变声+滤波+音频可视化 (535个子文件)
Cakefile 624B
mkdirp.cmd 182B
mime.cmd 170B
ipaddr.test.coffee 17KB
ipaddr.coffee 14KB
preamble.error 65B
.eslintignore 5B
.eslintrc 532B
.eslintrc 229B
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part7.header 117B
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preamble.header 91B
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part1.header 56B
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part6.header 55B
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part1.header 54B
part1.header 54B
index.html 9KB
encoding-indexes.js 541KB
encoding.js 63KB
_stream_readable.js 28KB
_stream_readable.js 25KB
response.js 25KB
index.js 22KB
index.js 21KB
parse.js 20KB
stringify.js 19KB
qs.js 18KB
test-types-multipart.js 16KB
_stream_writable.js 15KB
ipaddr.js 15KB
index.js 15KB
application.js 14KB
_stream_writable.js 13KB
request.js 12KB
index.js 10KB
index.js 10KB
parted-multipart.js 10KB
multipart.js 9KB
string_decoder.js 8KB
index.js 8KB
ipaddr.min.js 7KB
parse.js 7KB
_stream_transform.js 7KB
test-multipart.js 7KB
test-multipart-nolisteners.js 7KB
urlencoded.js 6KB
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Dicer.js 6KB
index.js 6KB
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stringify.js 6KB
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node.js 6KB
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utils.js 6KB
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parse.js 5KB
test-types-urlencoded.js 5KB
mediaType.js 5KB
make-middleware.js 5KB
index.js 5KB
utils.js 5KB
utils.js 5KB
browser.js 5KB
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