massive update, probably broken
[dotfiles/.git] / .config / coc / extensions / node_modules / coc-prettier / node_modules / debug / README.md
1 # debug
2 [![Build Status](https://travis-ci.org/debug-js/debug.svg?branch=master)](https://travis-ci.org/debug-js/debug)  [![Coverage Status](https://coveralls.io/repos/github/debug-js/debug/badge.svg?branch=master)](https://coveralls.io/github/debug-js/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)
3 [![OpenCollective](https://opencollective.com/debug/sponsors/badge.svg)](#sponsors)
4
5 <img width="647" src="https://user-images.githubusercontent.com/71256/29091486-fa38524c-7c37-11e7-895f-e7ec8e1039b6.png">
6
7 A tiny JavaScript debugging utility modelled after Node.js core's debugging
8 technique. Works in Node.js and web browsers.
9
10 ## Installation
11
12 ```bash
13 $ npm install debug
14 ```
15
16 ## Usage
17
18 `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.
19
20 Example [_app.js_](./examples/node/app.js):
21
22 ```js
23 var debug = require('debug')('http')
24   , http = require('http')
25   , name = 'My App';
26
27 // fake app
28
29 debug('booting %o', name);
30
31 http.createServer(function(req, res){
32   debug(req.method + ' ' + req.url);
33   res.end('hello\n');
34 }).listen(3000, function(){
35   debug('listening');
36 });
37
38 // fake worker of some kind
39
40 require('./worker');
41 ```
42
43 Example [_worker.js_](./examples/node/worker.js):
44
45 ```js
46 var a = require('debug')('worker:a')
47   , b = require('debug')('worker:b');
48
49 function work() {
50   a('doing lots of uninteresting work');
51   setTimeout(work, Math.random() * 1000);
52 }
53
54 work();
55
56 function workb() {
57   b('doing some work');
58   setTimeout(workb, Math.random() * 2000);
59 }
60
61 workb();
62 ```
63
64 The `DEBUG` environment variable is then used to enable these based on space or
65 comma-delimited names.
66
67 Here are some examples:
68
69 <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">
70 <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">
71 <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">
72
73 #### Windows command prompt notes
74
75 ##### CMD
76
77 On Windows the environment variable is set using the `set` command.
78
79 ```cmd
80 set DEBUG=*,-not_this
81 ```
82
83 Example:
84
85 ```cmd
86 set DEBUG=* & node app.js
87 ```
88
89 ##### PowerShell (VS Code default)
90
91 PowerShell uses different syntax to set environment variables.
92
93 ```cmd
94 $env:DEBUG = "*,-not_this"
95 ```
96
97 Example:
98
99 ```cmd
100 $env:DEBUG='app';node app.js
101 ```
102
103 Then, run the program to be debugged as usual.
104
105 npm script example:
106 ```js
107   "windowsDebug": "@powershell -Command $env:DEBUG='*';node app.js",
108 ```
109
110 ## Namespace Colors
111
112 Every debug instance has a color generated for it based on its namespace name.
113 This helps when visually parsing the debug output to identify which debug instance
114 a debug line belongs to.
115
116 #### Node.js
117
118 In Node.js, colors are enabled when stderr is a TTY. You also _should_ install
119 the [`supports-color`](https://npmjs.org/supports-color) module alongside debug,
120 otherwise debug will only use a small handful of basic colors.
121
122 <img width="521" src="https://user-images.githubusercontent.com/71256/29092181-47f6a9e6-7c3a-11e7-9a14-1928d8a711cd.png">
123
124 #### Web Browser
125
126 Colors are also enabled on "Web Inspectors" that understand the `%c` formatting
127 option. These are WebKit web inspectors, Firefox ([since version
128 31](https://hacks.mozilla.org/2014/05/editable-box-model-multiple-selection-sublime-text-keys-much-more-firefox-developer-tools-episode-31/))
129 and the Firebug plugin for Firefox (any version).
130
131 <img width="524" src="https://user-images.githubusercontent.com/71256/29092033-b65f9f2e-7c39-11e7-8e32-f6f0d8e865c1.png">
132
133
134 ## Millisecond diff
135
136 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.
137
138 <img width="647" src="https://user-images.githubusercontent.com/71256/29091486-fa38524c-7c37-11e7-895f-e7ec8e1039b6.png">
139
140 When stdout is not a TTY, `Date#toISOString()` is used, making it more useful for logging the debug information as shown below:
141
142 <img width="647" src="https://user-images.githubusercontent.com/71256/29091956-6bd78372-7c39-11e7-8c55-c948396d6edd.png">
143
144
145 ## Conventions
146
147 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".  If you append a "*" to the end of your name, it will always be enabled regardless of the setting of the DEBUG environment variable.  You can then use it for normal output as well as debug output.
148
149 ## Wildcards
150
151 The `*` character may be used as a wildcard. Suppose for example your library has
152 debuggers named "connect:bodyParser", "connect:compress", "connect:session",
153 instead of listing all three with
154 `DEBUG=connect:bodyParser,connect:compress,connect:session`, you may simply do
155 `DEBUG=connect:*`, or to run everything using this module simply use `DEBUG=*`.
156
157 You can also exclude specific debuggers by prefixing them with a "-" character.
158 For example, `DEBUG=*,-connect:*` would include all debuggers except those
159 starting with "connect:".
160
161 ## Environment Variables
162
163 When running through Node.js, you can set a few environment variables that will
164 change the behavior of the debug logging:
165
166 | Name      | Purpose                                         |
167 |-----------|-------------------------------------------------|
168 | `DEBUG`   | Enables/disables specific debugging namespaces. |
169 | `DEBUG_HIDE_DATE` | Hide date from debug output (non-TTY).  |
170 | `DEBUG_COLORS`| Whether or not to use colors in the debug output. |
171 | `DEBUG_DEPTH` | Object inspection depth.                    |
172 | `DEBUG_SHOW_HIDDEN` | Shows hidden properties on inspected objects. |
173
174
175 __Note:__ The environment variables beginning with `DEBUG_` end up being
176 converted into an Options object that gets used with `%o`/`%O` formatters.
177 See the Node.js documentation for
178 [`util.inspect()`](https://nodejs.org/api/util.html#util_util_inspect_object_options)
179 for the complete list.
180
181 ## Formatters
182
183 Debug uses [printf-style](https://wikipedia.org/wiki/Printf_format_string) formatting.
184 Below are the officially supported formatters:
185
186 | Formatter | Representation |
187 |-----------|----------------|
188 | `%O`      | Pretty-print an Object on multiple lines. |
189 | `%o`      | Pretty-print an Object all on a single line. |
190 | `%s`      | String. |
191 | `%d`      | Number (both integer and float). |
192 | `%j`      | JSON. Replaced with the string '[Circular]' if the argument contains circular references. |
193 | `%%`      | Single percent sign ('%'). This does not consume an argument. |
194
195
196 ### Custom formatters
197
198 You can add custom formatters by extending the `debug.formatters` object.
199 For example, if you wanted to add support for rendering a Buffer as hex with
200 `%h`, you could do something like:
201
202 ```js
203 const createDebug = require('debug')
204 createDebug.formatters.h = (v) => {
205   return v.toString('hex')
206 }
207
208 // â€¦elsewhere
209 const debug = createDebug('foo')
210 debug('this is hex: %h', new Buffer('hello world'))
211 //   foo this is hex: 68656c6c6f20776f726c6421 +0ms
212 ```
213
214
215 ## Browser Support
216
217 You can build a browser-ready script using [browserify](https://github.com/substack/node-browserify),
218 or just use the [browserify-as-a-service](https://wzrd.in/) [build](https://wzrd.in/standalone/debug@latest),
219 if you don't want to build it yourself.
220
221 Debug's enable state is currently persisted by `localStorage`.
222 Consider the situation shown below where you have `worker:a` and `worker:b`,
223 and wish to debug both. You can enable this using `localStorage.debug`:
224
225 ```js
226 localStorage.debug = 'worker:*'
227 ```
228
229 And then refresh the page.
230
231 ```js
232 a = debug('worker:a');
233 b = debug('worker:b');
234
235 setInterval(function(){
236   a('doing some work');
237 }, 1000);
238
239 setInterval(function(){
240   b('doing some work');
241 }, 1200);
242 ```
243
244
245 ## Output streams
246
247   By default `debug` will log to stderr, however this can be configured per-namespace by overriding the `log` method:
248
249 Example [_stdout.js_](./examples/node/stdout.js):
250
251 ```js
252 var debug = require('debug');
253 var error = debug('app:error');
254
255 // by default stderr is used
256 error('goes to stderr!');
257
258 var log = debug('app:log');
259 // set this namespace to log via console.log
260 log.log = console.log.bind(console); // don't forget to bind to console!
261 log('goes to stdout');
262 error('still goes to stderr!');
263
264 // set all output to go via console.info
265 // overrides all per-namespace log settings
266 debug.log = console.info.bind(console);
267 error('now goes to stdout via console.info');
268 log('still goes to stdout, but via console.info now');
269 ```
270
271 ## Extend
272 You can simply extend debugger 
273 ```js
274 const log = require('debug')('auth');
275
276 //creates new debug instance with extended namespace
277 const logSign = log.extend('sign');
278 const logLogin = log.extend('login');
279
280 log('hello'); // auth hello
281 logSign('hello'); //auth:sign hello
282 logLogin('hello'); //auth:login hello
283 ```
284
285 ## Set dynamically
286
287 You can also enable debug dynamically by calling the `enable()` method :
288
289 ```js
290 let debug = require('debug');
291
292 console.log(1, debug.enabled('test'));
293
294 debug.enable('test');
295 console.log(2, debug.enabled('test'));
296
297 debug.disable();
298 console.log(3, debug.enabled('test'));
299
300 ```
301
302 print :   
303 ```
304 1 false
305 2 true
306 3 false
307 ```
308
309 Usage :  
310 `enable(namespaces)`  
311 `namespaces` can include modes separated by a colon and wildcards.
312    
313 Note that calling `enable()` completely overrides previously set DEBUG variable : 
314
315 ```
316 $ DEBUG=foo node -e 'var dbg = require("debug"); dbg.enable("bar"); console.log(dbg.enabled("foo"))'
317 => false
318 ```
319
320 `disable()`
321
322 Will disable all namespaces. The functions returns the namespaces currently
323 enabled (and skipped). This can be useful if you want to disable debugging
324 temporarily without knowing what was enabled to begin with.
325
326 For example:
327
328 ```js
329 let debug = require('debug');
330 debug.enable('foo:*,-foo:bar');
331 let namespaces = debug.disable();
332 debug.enable(namespaces);
333 ```
334
335 Note: There is no guarantee that the string will be identical to the initial
336 enable string, but semantically they will be identical.
337
338 ## Checking whether a debug target is enabled
339
340 After you've created a debug instance, you can determine whether or not it is
341 enabled by checking the `enabled` property:
342
343 ```javascript
344 const debug = require('debug')('http');
345
346 if (debug.enabled) {
347   // do stuff...
348 }
349 ```
350
351 You can also manually toggle this property to force the debug instance to be
352 enabled or disabled.
353
354 ## Usage in child processes
355
356 Due to the way `debug` detects if the output is a TTY or not, colors are not shown in child processes when `stderr` is piped. A solution is to pass the `DEBUG_COLORS=1` environment variable to the child process.  
357 For example:
358
359 ```javascript
360 worker = fork(WORKER_WRAP_PATH, [workerPath], {
361   stdio: [
362     /* stdin: */ 0,
363     /* stdout: */ 'pipe',
364     /* stderr: */ 'pipe',
365     'ipc',
366   ],
367   env: Object.assign({}, process.env, {
368     DEBUG_COLORS: 1 // without this settings, colors won't be shown
369   }),
370 });
371
372 worker.stderr.pipe(process.stderr, { end: false });
373 ```
374
375
376 ## Authors
377
378  - TJ Holowaychuk
379  - Nathan Rajlich
380  - Andrew Rhyne
381  - Josh Junon
382
383 ## Backers
384
385 Support us with a monthly donation and help us continue our activities. [[Become a backer](https://opencollective.com/debug#backer)]
386
387 <a href="https://opencollective.com/debug/backer/0/website" target="_blank"><img src="https://opencollective.com/debug/backer/0/avatar.svg"></a>
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416 <a href="https://opencollective.com/debug/backer/29/website" target="_blank"><img src="https://opencollective.com/debug/backer/29/avatar.svg"></a>
417
418
419 ## Sponsors
420
421 Become a sponsor and get your logo on our README on Github with a link to your site. [[Become a sponsor](https://opencollective.com/debug#sponsor)]
422
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453
454 ## License
455
456 (The MIT License)
457
458 Copyright (c) 2014-2017 TJ Holowaychuk &lt;tj@vision-media.ca&gt;
459 Copyright (c) 2018-2021 Josh Junon
460
461 Permission is hereby granted, free of charge, to any person obtaining
462 a copy of this software and associated documentation files (the
463 'Software'), to deal in the Software without restriction, including
464 without limitation the rights to use, copy, modify, merge, publish,
465 distribute, sublicense, and/or sell copies of the Software, and to
466 permit persons to whom the Software is furnished to do so, subject to
467 the following conditions:
468
469 The above copyright notice and this permission notice shall be
470 included in all copies or substantial portions of the Software.
471
472 THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
473 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
474 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
475 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
476 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
477 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
478 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.