diff --git a/README.md b/README.md index 88dae35d..1ed84942 100644 --- a/README.md +++ b/README.md @@ -1,362 +1,270 @@ -# 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) +# Debug [![Build Status](https://img.shields.io/travis/visionmedia/debug/master?style=for-the-badge)](https://travis-ci.org/visionmedia/debug) [![Coverage Status](https://img.shields.io/coveralls/github/visionmedia/debug/master?style=for-the-badge)](https://coveralls.io/github/visionmedia/debug?branch=master) - - -A tiny JavaScript debugging utility modelled after Node.js core's debugging -technique. Works in Node.js and web browsers. +A tiny JavaScript debugging utility modelled after Node.js core's debugging technique. Works cross-platform in NodeJS and browsers. ## Installation -```bash -$ npm install debug +```sh +npm install debug ``` -## Usage +## Basic 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. +Debug exports a function which can be provided with the name of your package. The function it returns is essentially a decorated version of console.error which you can pass debug statements to. -Example [_app.js_](./examples/node/app.js): +This allows you to toggle the debug output for different parts of your module as well as the module as a whole. ```js -var debug = require('debug')('http') - , http = require('http') - , name = 'My App'; +const debug = require('debug')('http') -// fake app +const express = require('express') +const name = 'My App' +const app = express() -debug('booting %o', name); +debug(`Booting ${name}...`) -http.createServer(function(req, res){ - debug(req.method + ' ' + req.url); - res.end('hello\n'); -}).listen(3000, function(){ - debug('listening'); -}); +app.get('/', (req, res) => { + debug(`${app} called!`) + res.send('Hello World!') +}) -// fake worker of some kind +app.listen(8080, () => debug(`${name} listening on port ${port}!`)) -require('./worker'); +require('./worker') ``` -Example [_worker.js_](./examples/node/worker.js): +Example worker: ```js -var a = require('debug')('worker:a') - , b = require('debug')('worker:b'); +const a = require('debug')('worker:a') +const b = require('debug')('worker:b') function work() { - a('doing lots of uninteresting work'); - setTimeout(work, Math.random() * 1000); + a('doing lots of uninteresting work') + setTimeout(work, Math.random() * 1000) } -work(); +work() function workb() { - b('doing some work'); - setTimeout(workb, Math.random() * 2000); + b('doing some work') + setTimeout(workb, Math.random() * 2000) } -workb(); +workb() ``` -The `DEBUG` environment variable is then used to enable these based on space or -comma-delimited names. +The `DEBUG` environment variable is then used to enable these based on space or comma-delimited names or a wildcard: -Here are some examples: +Example terminal -screen shot 2017-08-08 at 12 53 04 pm -screen shot 2017-08-08 at 12 53 38 pm -screen shot 2017-08-08 at 12 53 25 pm +## API -#### Windows command prompt notes +### debug(namespace) -##### CMD +#### namespace -On Windows the environment variable is set using the `set` command. +Type: `string` -```cmd -set DEBUG=*,-not_this -``` +The name for `debug` to identify itself as. -Example: +### debug.formatters -```cmd -set DEBUG=* & node app.js -``` +Type: `object` -##### PowerShell (VS Code default) +An object of [printf-style](https://wikipedia.org/wiki/Printf_format_string) formatters which debug uses. -PowerShell uses different syntax to set environment variables. +Officially supported formatters: -```cmd -$env:DEBUG = "*,-not_this" -``` +| 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. | -Example: +You can add your own custom formatters by extending it. For example, if you wanted to add support for rendering a Buffer as hex with `%h`, you could do something like: -```cmd -$env:DEBUG='app';node app.js +```js +const createDebug = require('debug') +createDebug.formatters.h = (v) => { + return v.toString('hex') +} ``` -Then, run the program to be debugged as usual. +Elsewhere in your code, you can do: -npm script example: ```js - "windowsDebug": "@powershell -Command $env:DEBUG='*';node app.js", +const debug = createDebug('foo') +debug('this is hex: %h', new Buffer('hello world')) +//=> foo this is hex: 68656c6c6f20776f726c6421 +0ms ``` -## Namespace Colors +### Instance of `debug` -Every debug instance has a color generated for it based on its namespace name. -This helps when visually parsing the debug output to identify which debug instance -a debug line belongs to. +#### namespace -#### Node.js +Type: `string` -In Node.js, colors are enabled when stderr is a TTY. You also _should_ install -the [`supports-color`](https://npmjs.org/supports-color) module alongside debug, -otherwise debug will only use a small handful of basic colors. +The namespace that was specified in the initialiser function. - +#### enabled -#### Web Browser +Type: `boolean` +Default: (`true` when enable via environmental variable) -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). +Log debug messages. - +#### useColors +Type: `boolean`\ +Default: (`true` when supported) -## Millisecond diff +Use colors in the log messages. -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. +#### color - +Type: `number`\ +Default: (If `useColors` is `true`, default to a random colour) -When stdout is not a TTY, `Date#toISOString()` is used, making it more useful for logging the debug information as shown below: +The color to use in the log messages. - +#### destroy() +Remove the debug function and allow it to be garbage-collected. -## Conventions +#### extend(namespace, deliminer?) -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. +Extend the current namespace by appending it with another. -## Wildcards +##### namespace -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/disables specific debugging namespaces. | -| `DEBUG_HIDE_DATE` | Hide date from debug output (non-TTY). | -| `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. | +Type: `string` +The namespace to extend it by. -### Custom formatters +##### deliminer -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: +Type: `string`\ +Default: `:` -```js -const createDebug = require('debug') -createDebug.formatters.h = (v) => { - return v.toString('hex') -} +The deliminer to use for extending the namespace. -// …elsewhere -const debug = createDebug('foo') -debug('this is hex: %h', new Buffer('hello world')) -// foo this is hex: 68656c6c6f20776f726c6421 +0ms -``` +#### inspectOpts (NodeJS only) +Type: `object` -## Browser Support +##### colors -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. +Type: `number` -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`: +An array of colors which can be used in ANSI escape codes. -```js -localStorage.debug = 'worker:*' -``` +##### hideDate -And then refresh the page. +Type: `boolean` -```js -a = debug('worker:a'); -b = debug('worker:b'); +Hide the date when not using colors. -setInterval(function(){ - a('doing some work'); -}, 1000); +#### diff -setInterval(function(){ - b('doing some work'); -}, 1200); -``` +Type: `number` +The difference in milliseconds since the last debug message. -## Output streams +#### prev - By default `debug` will log to stderr, however this can be configured per-namespace by overriding the `log` method: +Type: `number` -Example [_stdout.js_](./examples/node/stdout.js): +The timestamp on which the previous debug message was logged. -```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'); -``` +#### curr -## Extend -You can simply extend debugger -```js -const log = require('debug')('auth'); +Type: `number` -//creates new debug instance with extended namespace -const logSign = log.extend('sign'); -const logLogin = log.extend('login'); +The timestamp on which the current debug message was logged. -log('hello'); // auth hello -logSign('hello'); //auth:sign hello -logLogin('hello'); //auth:login hello -``` +## Extra information -## Set dynamically +### Environment Variables -You can also enable debug dynamically by calling the `enable()` method : +When running `debug` in NodeJS, you can set a few environment variables that can change the behavior of the debug logging: -```js -let debug = require('debug'); +| Name | Purpose | +|---------------------|---------------------------------------------------| +| `DEBUG` | Enables/disables specific debugging namespaces. | +| `DEBUG_HIDE_DATE` | Hide date from debug output (non-TTY). | +| `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. | -console.log(1, debug.enabled('test')); -debug.enable('test'); -console.log(2, debug.enabled('test')); +__Note:__ The environment variables that begin with `DEBUG_` end up being +converted into an Options object that is used with `%o`/`%O` formatters. -debug.disable(); -console.log(3, debug.enabled('test')); +See the [`util.inspect()`](https://nodejs.org/api/util.html#util_util_inspect_object_options) NodeJS documentation for the complete list. -``` +### Conventions -print : -``` -1 false -2 true -3 false -``` +If you're using this in one or more of your libraries, you _should_ use the name of your library so that developers can toggle debugging as desired without guessing names. If you have more than one debugger 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 how the DEBUG environment variable is set. You can then use it for normal output as well as debug output. -Usage : -`enable(namespaces)` -`namespaces` can include modes separated by a colon and wildcards. - -Note that calling `enable()` completely overrides previously set DEBUG variable : +### Wildcards -``` -$ DEBUG=foo node -e 'var dbg = require("debug"); dbg.enable("bar"); console.log(dbg.enabled("foo"))' -=> false -``` +The `*` character may be used as a wildcard. Suppose for example your library has +debuggers named `connect:bodyParser`, `connect:compress` and `connect:session`. -`disable()` +Instead of listing all three with `DEBUG=connect:bodyParser,connect:compress,connect:session`, you can simply use `DEBUG=connect:*` and to run everything using this module, you can use `DEBUG=*`. -Will disable all namespaces. The functions returns the namespaces currently -enabled (and skipped). This can be useful if you want to disable debugging -temporarily without knowing what was enabled to begin with. +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:". -For example: +### Windows command prompt -```js -let debug = require('debug'); -debug.enable('foo:*,-foo:bar'); -let namespaces = debug.disable(); -debug.enable(namespaces); +#### CMD + +On Windows, the environment variable is set using the `set` command. + +```cmd +set DEBUG=*,-not_this ``` -Note: There is no guarantee that the string will be identical to the initial -enable string, but semantically they will be identical. +Example: -## Checking whether a debug target is enabled +```cmd +set DEBUG=* & node app.js +``` -After you've created a debug instance, you can determine whether or not it is -enabled by checking the `enabled` property: +#### PowerShell (VS Code default) -```javascript -const debug = require('debug')('http'); +PowerShell uses a different syntax to set environment variables. -if (debug.enabled) { - // do stuff... -} +```cmd +$env:DEBUG = "*,-not_this" ``` -You can also manually toggle this property to force the debug instance to be -enabled or disabled. +For example: + +```cmd +$env:DEBUG='app';node app.js +``` + +Then, you can run the program to be debugged as usual. +NPM script example: +```json +{ + "scripts": { + "windowsDebug": "@powershell -Command $env:DEBUG='*';node app.js" + } +} +``` ## Authors - - TJ Holowaychuk - - Nathan Rajlich - - Andrew Rhyne +| [![TJ Holowaychuk](https://github.com/tj.png?size=100)](https://github.com/tj) | [![Nathan Rajlich](https://github.com/tootallnate.png?size=100)](https://github.com/tootallnate) | [![Andrew Rhyne](https://github.com/thebigredgeek.png?size=100)](https://github.com/thebigredgeek) | +|-----------|-----------|-----------| +| TJ Holowaychuk | Nathan Rajlich | Andrew Rhyne | ## Backers @@ -433,7 +341,7 @@ Become a sponsor and get your logo on our README on Github with a link to your s (The MIT License) -Copyright (c) 2014-2017 TJ Holowaychuk <tj@vision-media.ca> +Copyright (c) 2014-2019 TJ Holowaychuk <tj@vision-media.ca> Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the @@ -453,3 +361,5 @@ IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + +> README rewrite by [@Richienb](https://github.com/Richienb)