comunicationLeap/node_modules/debug/Readme.md
node_modules/debug/Readme.mdRaw
1# debug
2
3 tiny node.js debugging utility modelled after node core's debugging technique.
4
5## Installation
6
7```bash
8$ npm install debug
9```
10
11## Usage
12
13 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.
14
15Example _app.js_:
16
17```js
18var debug = require('debug')('http')
19 , http = require('http')
20 , name = 'My App';
21
22// fake app
23
24debug('booting %s', name);
25
26http.createServer(function(req, res){
27 debug(req.method + ' ' + req.url);
28 res.end('hello\n');
29}).listen(3000, function(){
30 debug('listening');
31});
32
33// fake worker of some kind
34
35require('./worker');
36```
37
38Example _worker.js_:
39
40```js
41var debug = require('debug')('worker');
42
43setInterval(function(){
44 debug('doing some work');
45}, 1000);
46```
47
48 The __DEBUG__ environment variable is then used to enable these based on space or comma-delimited names. Here are some examples:
49
50 
51
52 
53
54#### Windows note
55
56 On Windows the environment variable is set using the `set` command.
57
58 ```cmd
59 set DEBUG=*,-not_this
60 ```
61
62Then, run the program to be debugged as usual.
63
64## Millisecond diff
65
66 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.
67
68 
69
70 When stdout is not a TTY, `Date#toUTCString()` is used, making it more useful for logging the debug information as shown below:
71
72 
73
74## Conventions
75
76 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".
77
78## Wildcards
79
80 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=*`.
81
82 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:".
83
84## Browser support
85
86 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:
87
88```js
89window.myDebug = require("debug");
90```
91
92 ("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:
93
94```js
95myDebug.enable("worker:*")
96```
97
98 Refresh the page. Debug output will continue to be sent to the console until it is disabled by typing `myDebug.disable()` in the console.
99
100```js
101a = debug('worker:a');
102b = debug('worker:b');
103
104setInterval(function(){
105 a('doing some work');
106}, 1000);
107
108setInterval(function(){
109 b('doing some work');
110}, 1200);
111```
112
113#### Web Inspector Colors
114
115 Colors are also enabled on "Web Inspectors" that understand the `%c` formatting
116 option. These are WebKit web inspectors, Firefox ([since version
117 31](https://hacks.mozilla.org/2014/05/editable-box-model-multiple-selection-sublime-text-keys-much-more-firefox-developer-tools-episode-31/))
118 and the Firebug plugin for Firefox (any version).
119
120 Colored output looks something like:
121
122 
123
124### stderr vs stdout
125
126You can set an alternative logging method per-namespace by overriding the `log` method on a per-namespace or globally:
127
128Example _stdout.js_:
129
130```js
131var debug = require('debug');
132var error = debug('app:error');
133
134// by default stderr is used
135error('goes to stderr!');
136
137var log = debug('app:log');
138// set this namespace to log via console.log
139log.log = console.log.bind(console); // don't forget to bind to console!
140log('goes to stdout');
141error('still goes to stderr!');
142
143// set all output to go via console.info
144// overrides all per-namespace log settings
145debug.log = console.info.bind(console);
146error('now goes to stdout via console.info');
147log('still goes to stdout, but via console.info now');
148```
149
150### Save debug output to a file
151
152You can save all debug statements to a file by piping them.
153
154Example:
155
156```bash
157$ DEBUG_FD=3 node your-app.js 3> whatever.log
158```
159
160## Authors
161
162 - TJ Holowaychuk
163 - Nathan Rajlich
164
165## License
166
167(The MIT License)
168
169Copyright (c) 2014 TJ Holowaychuk <tj@vision-media.ca>
170
171Permission is hereby granted, free of charge, to any person obtaining
172a copy of this software and associated documentation files (the
173'Software'), to deal in the Software without restriction, including
174without limitation the rights to use, copy, modify, merge, publish,
175distribute, sublicense, and/or sell copies of the Software, and to
176permit persons to whom the Software is furnished to do so, subject to
177the following conditions:
178
179The above copyright notice and this permission notice shall be
180included in all copies or substantial portions of the Software.
181
182THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
183EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
184MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
185IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
186CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
187TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
188SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.