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Inquirer.js

A collection of common interactive command line user interfaces.

Goal and Philosophy

**Inquirer.js** strives to be an easily embeddable and beautiful command line interface for Node.js (and perhaps the "CLI [Xanadu](https://en.wikipedia.org/wiki/Citizen_Kane)").

**Inquirer.js** should ease the process of

providing error feedback
asking questions
parsing input
validating answers
managing hierarchical prompts

Note: **Inquirer.js** provides the user interface and the inquiry session flow. If you're searching for a full blown command line program utility, then check out commander, vorpal or args.

<a href="#documentation">Documentation</a>

Installation

npm install inquirer

var inquirer = require('inquirer');
inquirer
  .prompt([
    /* Pass your questions in here */
  ])
  .then(answers => {
    // Use user feedback for... whatever!!
  })
  .catch(error => {
    if(error.isTtyError) {
      // Prompt couldn't be rendered in the current environment
    } else {
      // Something else when wrong
    }
  }); 

Examples (Run it and see it)

Check out the packages/inquirer/examples/ folder for code and interface examples.

node packages/inquirer/examples/pizza.js
node packages/inquirer/examples/checkbox.js
# etc... 

Methods

<tt>inquirer.prompt(questions) -> promise</tt>

Launch the prompt interface (inquiry session)

questions (Array) containing Question Object (using the reactive interface, you can also pass a Rx.Observable instance)
returns a Promise

<tt>inquirer.registerPrompt(name, prompt)</tt>

Register prompt plugins under name.

name (string) name of the this new prompt. (used for question type)
prompt (object) the prompt object itself (the plugin)

<tt>inquirer.createPromptModule() -> prompt function</tt>

Create a self contained inquirer module. If you don't want to affect other libraries that also rely on inquirer when you overwrite or add new prompt types.

var prompt = inquirer.createPromptModule();
 
prompt(questions).then(/* ... */); 

Objects

Question

A question object is a hash containing question related values:

type: (String) Type of the prompt. Defaults: input - Possible values: input, number, confirm, list, rawlist, expand, checkbox, password, editor
name: (String) The name to use when storing the answer in the answers hash. If the name contains periods, it will define a path in the answers hash.
message: (String|Function) The question to print. If defined as a function, the first parameter will be the current inquirer session answers. Defaults to the value of name (followed by a colon).
default: (String|Number|Boolean|Array|Function) Default value(s) to use if nothing is entered, or a function that returns the default value(s). If defined as a function, the first parameter will be the current inquirer session answers.
choices: (Array|Function) Choices array or a function returning a choices array. If defined as a function, the first parameter will be the current inquirer session answers. Array values can be simple numbers, strings, or objects containing a name (to display in list), a value (to save in the answers hash), and a short (to display after selection) properties. The choices array can also contain a Separator.
validate: (Function) Receive the user input and answers hash. Should return true if the value is valid, and an error message (String) otherwise. If false is returned, a default error message is provided.
filter: (Function) Receive the user input and answers hash. Returns the filtered value to be used inside the program. The value returned will be added to the Answers hash.
transformer: (Function) Receive the user input, answers hash and option flags, and return a transformed value to display to the user. The transformation only impacts what is shown while editing. It does not modify the answers hash.
when: (Function, Boolean) Receive the current user answers hash and should return true or false depending on whether or not this question should be asked. The value can also be a simple boolean.
pageSize: (Number) Change the number of lines that will be rendered when using list, rawList, expand or checkbox.
prefix: (String) Change the default prefix message.
suffix: (String) Change the default suffix message.
askAnswered: (Boolean) Force to prompt the question if the answer already exists.
loop: (Boolean) Enable list looping. Defaults: true

default, choices(if defined as functions), validate, filter and when functions can be called asynchronously. Either return a promise or use this.async() to get a callback you'll call with the final value.

{
  /* Preferred way: with promise */
  filter() {
    return new Promise(/* etc... */);
  },
 
  /* Legacy way: with this.async */
  validate: function (input) {
    // Declare function as asynchronous, and save the done callback
    var done = this.async();
 
    // Do async stuff
    setTimeout(function() {
      if (typeof input !== 'number') {
        // Pass the return value in the done callback
        done('You need to provide a number');
        return;
      }
      // Pass the return value in the done callback
      done(null, true);
    }, 3000);
  }
} 

Answers

A key/value hash containing the client answers in each prompt.

Key The name property of the question object
Value (Depends on the prompt)
- confirm: (Boolean)
- input : User input (filtered if filter is defined) (String)
- number: User input (filtered if filter is defined) (Number)
- rawlist, list : Selected choice value (or name if no value specified) (String)

Separator

A separator can be added to any choices array:

// In the question object
choices: [ "Choice A", new inquirer.Separator(), "choice B" ]
 
// Which'll be displayed this way
[?] What do you want to do?
 > Order a pizza
   Make a reservation
   --------
   Ask opening hours
   Talk to the receptionist 

The constructor takes a facultative String value that'll be use as the separator. If omitted, the separator will be --------.

Separator instances have a property type equal to separator. This should allow tools façading Inquirer interface from detecting separator types in lists.

Prompt types

Note:: _allowed options written inside square brackets ([]) are optional. Others are required._

List - ‘{type: 'list’}`

Take type, name, message, choices[, default, filter, loop] properties. (Note that default must be the choice index in the array or a choice value)

List prompt

Raw List - ‘{type: 'rawlist’}`

Take type, name, message, choices[, default, filter, loop] properties. (Note that default must be the choice index in the array)

Raw list prompt

Expand - ‘{type: 'expand’}`

Take type, name, message, choices[, default] properties. (Note that default must be the choice index in the array. If default key not provided, then help will be used as default choice)

Note that the choices object will take an extra parameter called key for the expand prompt. This parameter must be a single (lowercased) character. The h option is added by the prompt and shouldn't be defined by the user.

See examples/expand.js for a running example.

Checkbox - ‘{type: 'checkbox’}`

Take type, name, message, choices[, filter, validate, default, loop] properties. default is expected to be an Array of the checked choices value.

Choices marked as {checked: true} will be checked by default.

Choices whose property disabled is truthy will be unselectable. If disabled is a string, then the string will be outputted next to the disabled choice, otherwise it'll default to "Disabled". The disabled property can also be a synchronous function receiving the current answers as argument and returning a boolean or a string.

Checkbox prompt

Confirm - ‘{type: 'confirm’}`

Take type, name, message, [default] properties. default is expected to be a boolean if used.

Confirm prompt

Input - ‘{type: 'input’}`

Take type, name, message[, default, filter, validate, transformer] properties.

Input prompt

Input - ‘{type: 'number’}`

Take type, name, message[, default, filter, validate, transformer] properties.

Password - ‘{type: 'password’}`

Take type, name, message, mask,[, default, filter, validate] properties.

Password prompt

Note that mask is required to hide the actual user input.

Editor - ‘{type: 'editor’}`

Take type, name, message[, default, filter, validate] properties

Launches an instance of the users preferred editor on a temporary file. Once the user exits their editor, the contents of the temporary file are read in as the result. The editor to use is determined by reading the $VISUAL or $EDITOR environment variables. If neither of those are present, notepad (on Windows) or vim (Linux or Mac) is used.

Use in Non-Interactive Environments

prompt() requires that it is run in an interactive environment. (I.e. One where process.stdin.isTTY is true). If prompt() is invoked outside of such an environment, then prompt() will return a rejected promise with an error. For convenience, the error will have a isTtyError property to programmatically indicate the cause.

User Interfaces and layouts

Along with the prompts, Inquirer offers some basic text UI.

Bottom Bar - <tt>inquirer.ui.BottomBar</tt>

This UI present a fixed text at the bottom of a free text zone. This is useful to keep a message to the bottom of the screen while outputting command outputs on the higher section.

var ui = new inquirer.ui.BottomBar();
 
// pipe a Stream to the log zone
outputStream.pipe(ui.log);
 
// Or simply write output
ui.log.write('something just happened.');
ui.log.write('Almost over, standby!');
 
// During processing, update the bottom bar content to display a loader
// or output a progress bar, etc
ui.updateBottomBar('new bottom bar content'); 

Reactive interface

Internally, Inquirer uses the JS reactive extension to handle events and async flows.

This mean you can take advantage of this feature to provide more advanced flows. For example, you can dynamically add questions to be asked:

var prompts = new Rx.Subject();
inquirer.prompt(prompts);
 
// At some point in the future, push new questions
prompts.next({
  /* question... */
});
prompts.next({
  /* question... */
});
 
// When you're done
prompts.complete(); 

And using the return value process property, you can access more fine grained callbacks:

inquirer.prompt(prompts).ui.process.subscribe(onEachAnswer, onError, onComplete);

Support (OS Terminals)

You should expect mostly good support for the CLI below. This does not mean we won't look at issues found on other command line - feel free to report any!

Mac OS:
- Terminal.app
- iTerm
Windows (Known issues):
- ConEmu
- cmd.exe
- Powershell
- Cygwin
Linux (Ubuntu, openSUSE, Arch Linux, etc):
- gnome-terminal (Terminal GNOME)
- konsole

Know issues

Running Inquirer together with network streams in Windows platform inside some terminals can result in process hang. Workaround: run inside another terminal. Please refer to the https://github.com/nodejs/node/issues/21771

News on the march (Release notes)

Please refer to the GitHub releases section for the changelog

Contributing

Unit test Unit test are written in Mocha. Please add a unit test for every new feature or bug fix. npm test to run the test suite.

Documentation Add documentation for every API change. Feel free to send typo fixes and better docs!

We're looking to offer good support for multiple prompts and environments. If you want to help, we'd like to keep a list of testers for each terminal/OS so we can contact you and get feedback before release. Let us know if you want to be added to the list (just tweet to @vaxilart) or just add your name to the wiki