.config/coc/extensions/node_modules/coc-prettier/node_modules/stylelint/node_modules/debug/README.md

   1 # debug
   2 [![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)
   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 // …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 ## Checking whether a debug target is enabled
 321
 322 After you've created a debug instance, you can determine whether or not it is
 323 enabled by checking the `enabled` property:
 324
 325 ```javascript
 326 const debug = require('debug')('http');
 327
 328 if (debug.enabled) {
 329   // do stuff...
 330 }
 331 ```
 332
 333 You can also manually toggle this property to force the debug instance to be
 334 enabled or disabled.
 335
 336
 337 ## Authors
 338
 339  - TJ Holowaychuk
 340  - Nathan Rajlich
 341  - Andrew Rhyne
 342
 343 ## Backers
 344
 345 Support us with a monthly donation and help us continue our activities. [[Become a backer](https://opencollective.com/debug#backer)]
 346
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 377
 378
 379 ## Sponsors
 380
 381 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)]
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 400 <a href="https://opencollective.com/debug/sponsor/17/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/17/avatar.svg"></a>
 401 <a href="https://opencollective.com/debug/sponsor/18/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/18/avatar.svg"></a>
 402 <a href="https://opencollective.com/debug/sponsor/19/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/19/avatar.svg"></a>
 403 <a href="https://opencollective.com/debug/sponsor/20/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/20/avatar.svg"></a>
 404 <a href="https://opencollective.com/debug/sponsor/21/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/21/avatar.svg"></a>
 405 <a href="https://opencollective.com/debug/sponsor/22/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/22/avatar.svg"></a>
 406 <a href="https://opencollective.com/debug/sponsor/23/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/23/avatar.svg"></a>
 407 <a href="https://opencollective.com/debug/sponsor/24/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/24/avatar.svg"></a>
 408 <a href="https://opencollective.com/debug/sponsor/25/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/25/avatar.svg"></a>
 409 <a href="https://opencollective.com/debug/sponsor/26/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/26/avatar.svg"></a>
 410 <a href="https://opencollective.com/debug/sponsor/27/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/27/avatar.svg"></a>
 411 <a href="https://opencollective.com/debug/sponsor/28/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/28/avatar.svg"></a>
 412 <a href="https://opencollective.com/debug/sponsor/29/website" target="_blank"><img src="https://opencollective.com/debug/sponsor/29/avatar.svg"></a>
 413
 414 ## License
 415
 416 (The MIT License)
 417
 418 Copyright (c) 2014-2017 TJ Holowaychuk &lt;tj@vision-media.ca&gt;
 419
 420 Permission is hereby granted, free of charge, to any person obtaining
 421 a copy of this software and associated documentation files (the
 422 'Software'), to deal in the Software without restriction, including
 423 without limitation the rights to use, copy, modify, merge, publish,
 424 distribute, sublicense, and/or sell copies of the Software, and to
 425 permit persons to whom the Software is furnished to do so, subject to
 426 the following conditions:
 427
 428 The above copyright notice and this permission notice shall be
 429 included in all copies or substantial portions of the Software.
 430
 431 THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
 432 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 433 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 434 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 435 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 436 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 437 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.