promptly

Simple command line prompting utility.

Installation

$ npm install promptly

API

.prompt(message, [options])

Prompts for a value, printing the message and waiting for the input.
Returns a promise that resolves with the input.

Available options:

Name	Description	Type	Default
default	The default value to use if the user provided an empty input	string	undefined
trim	Trims the user input	boolean	true
validator	A validator or an array of validators	function/array	undefined
retry	Retry if any of the validators fail	boolean	true
silent	Do not print what the user types	boolean	false
replace	Replace each character with the specified string when silent is true	string	''
input	Input stream to read from	Stream	process.stdin
output	Output stream to write to	Stream	process.stdout
timeout	Timeout in ms	number	0
useDefaultOnTimeout	Return default value if timed out	boolean	false

The same options are available to all functions but with different default values.

Examples

• Ask for a name:

  const promptly = require('promptly');
   
  (async () => {
      const name = await promptly.prompt('Name: ');
      console.log(name);
  })();

• Ask for a name with a constraint (non-empty value and length > 2):

  const promptly = require('promptly');
   
  const validator = function (value) {
      if (value.length < 2) {
          throw new Error('Min length of 2');
      }
   
      return value;
  };
   
  (async () => {
      const name = await promptly.prompt('Name: ', { validator });
      // Since retry is true by default, promptly will keep asking for a name until it is valid
      // Between each prompt, the error message from the validator will be printed
      console.log('Name is:', name);
  })();
   

• Same as above but do not retry automatically:

  const promptly = require('promptly');
   
  const validator = function (value) {
      if (value.length < 2) {
          throw new Error('Min length of 2');
      }
   
      return value;
  };
   
  (async () => {
      try {
          const name = await promptly.prompt('Name: ', { validator, retry: false });
          console.log('Name is:', name);
      } catch (err) {
          console.error('Invalid name:')
          console.error(`- ${err.message}`);
      }
  })();

• Ask for a name with timeout:

  const promptly = require('promptly');
   
  (async () => {
      const name = await promptly.prompt('Name: ', { timeout: 3000 });
      console.log(name);
  })();

  It throws an Error("timed out") if timeout is reached and no default value is provided

Validators

The validators have two purposes: to check and transform input. They can be asynchronous or synchronous

const validator = (value) => {
    // Validation example, throwing an error when invalid
    if (value.length !== 2) {
        throw new Error('Length must be 2');
    }
 
    // Parse the value, modifying it
    return value.replace('aa', 'bb');
}
 
const asyncValidator = async (value) => {
    await myfunc();
    return value;
}

.confirm(message, [options])

Ask the user for confirmation, printing the message and waiting for the input.
Returns a promise that resolves with the answer.

Truthy values are: y, yes and 1. Falsy values are n, no, and 0.
Comparison is made in a case insensitive way.

The options are the same as prompt, except that trim defaults to false.

Examples

• Ask to confirm something important:

  const promptly = require('promptly');
   
  (async () => {
      const answer = await promptly.confirm('Are you really sure? ');
   
      console.log('Answer:', answer);
  })();

.choose(message, choices, [options])

Ask the user to choose between multiple choices (array of choices), printing the message and waiting for the input.
Returns a promise that resolves with the choice.

The options are the same as prompt, except that trim defaults to false.

Examples

• Ask to choose between:

  const promptly = require('promptly');
   
  (async () => {
      const choice = await promptly.choose('Do you want an apple or an orange? ', ['apple', 'orange']);
   
      console.log('Choice:', choice);
  })();

.password(message, [options])

Prompts for a password, printing the message and waiting for the input.
Returns a promise that resolves with the password.

The options are the same as prompt, except that trim and silent default to false and default is an empty string (to allow empty passwords).

Examples

• Ask for a password:

  const promptly = require('promptly');
   
  (async () => {
      const password = await promptly.password('Type a password: ');
   
      console.log('Password:', password);
  })();

• Ask for a password but mask the input with *:

  const promptly = require('promptly');
   
  (async () => {
      const password = await promptly.password('Type a password: ', { replace: '*' });
   
      console.log('Password:', password);
  })();

Tests

$ npm test
$ npm test -- --watch during development

License

Released under the MIT License.