twitst4tz

twitter statistics web application
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README.md (17918B)


      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 
      6 
      7 A tiny node.js debugging utility modelled after node core's debugging technique.
      8 
      9 **Discussion around the V3 API is under way [here](https://github.com/visionmedia/debug/issues/370)**
     10 
     11 ## Installation
     12 
     13 ```bash
     14 $ npm install debug
     15 ```
     16 
     17 ## Usage
     18 
     19 `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.
     20 
     21 Example _app.js_:
     22 
     23 ```js
     24 var debug = require('debug')('http')
     25   , http = require('http')
     26   , name = 'My App';
     27 
     28 // fake app
     29 
     30 debug('booting %s', name);
     31 
     32 http.createServer(function(req, res){
     33   debug(req.method + ' ' + req.url);
     34   res.end('hello\n');
     35 }).listen(3000, function(){
     36   debug('listening');
     37 });
     38 
     39 // fake worker of some kind
     40 
     41 require('./worker');
     42 ```
     43 
     44 Example _worker.js_:
     45 
     46 ```js
     47 var debug = require('debug')('worker');
     48 
     49 setInterval(function(){
     50   debug('doing some work');
     51 }, 1000);
     52 ```
     53 
     54  The __DEBUG__ environment variable is then used to enable these based on space or comma-delimited names. Here are some examples:
     55 
     56   ![debug http and worker](http://f.cl.ly/items/18471z1H402O24072r1J/Screenshot.png)
     57 
     58   ![debug worker](http://f.cl.ly/items/1X413v1a3M0d3C2c1E0i/Screenshot.png)
     59 
     60 #### Windows note
     61 
     62  On Windows the environment variable is set using the `set` command.
     63 
     64  ```cmd
     65  set DEBUG=*,-not_this
     66  ```
     67 
     68  Note that PowerShell uses different syntax to set environment variables.
     69 
     70  ```cmd
     71  $env:DEBUG = "*,-not_this"
     72   ```
     73 
     74 Then, run the program to be debugged as usual.
     75 
     76 ## Millisecond diff
     77 
     78   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.
     79 
     80   ![](http://f.cl.ly/items/2i3h1d3t121M2Z1A3Q0N/Screenshot.png)
     81 
     82   When stdout is not a TTY, `Date#toUTCString()` is used, making it more useful for logging the debug information as shown below:
     83 
     84   ![](http://f.cl.ly/items/112H3i0e0o0P0a2Q2r11/Screenshot.png)
     85 
     86 ## Conventions
     87 
     88   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".
     89 
     90 ## Wildcards
     91 
     92   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=*`.
     93 
     94   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:".
     95 
     96 ## Environment Variables
     97 
     98   When running through Node.js, you can set a few environment variables that will
     99   change the behavior of the debug logging:
    100 
    101 | Name      | Purpose                                         |
    102 |-----------|-------------------------------------------------|
    103 | `DEBUG`   | Enables/disables specific debugging namespaces. |
    104 | `DEBUG_COLORS`| Whether or not to use colors in the debug output. |
    105 | `DEBUG_DEPTH` | Object inspection depth. |
    106 | `DEBUG_SHOW_HIDDEN` | Shows hidden properties on inspected objects. |
    107 
    108 
    109   __Note:__ The environment variables beginning with `DEBUG_` end up being
    110   converted into an Options object that gets used with `%o`/`%O` formatters.
    111   See the Node.js documentation for
    112   [`util.inspect()`](https://nodejs.org/api/util.html#util_util_inspect_object_options)
    113   for the complete list.
    114 
    115 ## Formatters
    116 
    117 
    118   Debug uses [printf-style](https://wikipedia.org/wiki/Printf_format_string) formatting. Below are the officially supported formatters:
    119 
    120 | Formatter | Representation |
    121 |-----------|----------------|
    122 | `%O`      | Pretty-print an Object on multiple lines. |
    123 | `%o`      | Pretty-print an Object all on a single line. |
    124 | `%s`      | String. |
    125 | `%d`      | Number (both integer and float). |
    126 | `%j`      | JSON. Replaced with the string '[Circular]' if the argument contains circular references. |
    127 | `%%`      | Single percent sign ('%'). This does not consume an argument. |
    128 
    129 ### Custom formatters
    130 
    131   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:
    132 
    133 ```js
    134 const createDebug = require('debug')
    135 createDebug.formatters.h = (v) => {
    136   return v.toString('hex')
    137 }
    138 
    139 // …elsewhere
    140 const debug = createDebug('foo')
    141 debug('this is hex: %h', new Buffer('hello world'))
    142 //   foo this is hex: 68656c6c6f20776f726c6421 +0ms
    143 ```
    144 
    145 ## Browser support
    146   You can build a browser-ready script using [browserify](https://github.com/substack/node-browserify),
    147   or just use the [browserify-as-a-service](https://wzrd.in/) [build](https://wzrd.in/standalone/debug@latest),
    148   if you don't want to build it yourself.
    149 
    150   Debug's enable state is currently persisted by `localStorage`.
    151   Consider the situation shown below where you have `worker:a` and `worker:b`,
    152   and wish to debug both. You can enable this using `localStorage.debug`:
    153 
    154 ```js
    155 localStorage.debug = 'worker:*'
    156 ```
    157 
    158 And then refresh the page.
    159 
    160 ```js
    161 a = debug('worker:a');
    162 b = debug('worker:b');
    163 
    164 setInterval(function(){
    165   a('doing some work');
    166 }, 1000);
    167 
    168 setInterval(function(){
    169   b('doing some work');
    170 }, 1200);
    171 ```
    172 
    173 #### Web Inspector Colors
    174 
    175   Colors are also enabled on "Web Inspectors" that understand the `%c` formatting
    176   option. These are WebKit web inspectors, Firefox ([since version
    177   31](https://hacks.mozilla.org/2014/05/editable-box-model-multiple-selection-sublime-text-keys-much-more-firefox-developer-tools-episode-31/))
    178   and the Firebug plugin for Firefox (any version).
    179 
    180   Colored output looks something like:
    181 
    182   ![](https://cloud.githubusercontent.com/assets/71256/3139768/b98c5fd8-e8ef-11e3-862a-f7253b6f47c6.png)
    183 
    184 
    185 ## Output streams
    186 
    187   By default `debug` will log to stderr, however this can be configured per-namespace by overriding the `log` method:
    188 
    189 Example _stdout.js_:
    190 
    191 ```js
    192 var debug = require('debug');
    193 var error = debug('app:error');
    194 
    195 // by default stderr is used
    196 error('goes to stderr!');
    197 
    198 var log = debug('app:log');
    199 // set this namespace to log via console.log
    200 log.log = console.log.bind(console); // don't forget to bind to console!
    201 log('goes to stdout');
    202 error('still goes to stderr!');
    203 
    204 // set all output to go via console.info
    205 // overrides all per-namespace log settings
    206 debug.log = console.info.bind(console);
    207 error('now goes to stdout via console.info');
    208 log('still goes to stdout, but via console.info now');
    209 ```
    210 
    211 
    212 ## Authors
    213 
    214  - TJ Holowaychuk
    215  - Nathan Rajlich
    216  - Andrew Rhyne
    217  
    218 ## Backers
    219 
    220 Support us with a monthly donation and help us continue our activities. [[Become a backer](https://opencollective.com/debug#backer)]
    221 
    222 <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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    252 
    253 
    254 ## Sponsors
    255 
    256 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)]
    257 
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    288 
    289 ## License
    290 
    291 (The MIT License)
    292 
    293 Copyright (c) 2014-2016 TJ Holowaychuk &lt;tj@vision-media.ca&gt;
    294 
    295 Permission is hereby granted, free of charge, to any person obtaining
    296 a copy of this software and associated documentation files (the
    297 'Software'), to deal in the Software without restriction, including
    298 without limitation the rights to use, copy, modify, merge, publish,
    299 distribute, sublicense, and/or sell copies of the Software, and to
    300 permit persons to whom the Software is furnished to do so, subject to
    301 the following conditions:
    302 
    303 The above copyright notice and this permission notice shall be
    304 included in all copies or substantial portions of the Software.
    305 
    306 THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
    307 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    308 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
    309 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
    310 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
    311 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    312 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.