A beautiful command-line prompt for node.js
- prompts the user for input
- supports validation and defaults
- hides passwords
Using prompt is relatively straight forward. There are two core methods you should be aware of: prompt.get() and prompt.addProperties(). Their methods take strings representing property names in addition to objects for complex property validation (and more). There are a number of examples that you should examine for detailed usage.
Getting started with prompt is easy. Lets take a look at examples/simple-prompt.js:
var prompt = require('prompt');
//
// Start the prompt
//
prompt.start();
//
// Get two properties from the user: username and email
//
prompt.get(['username', 'email'], function (err, result) {
//
// Log the results.
//
console.log('Command-line input received:');
console.log(' username: ' + result.username);
console.log(' email: ' + result.email);
});This will result in the following command-line output:
$ node examples/simple-prompt.js
prompt: username: some-user
prompt: email: [email protected]
Command-line input received:
username: some-user
email: [email protected]
If no callback is passed to prompt.get(schema), then it returns a Promise, so you can also write:
const {username, email} = await prompt.get(['username', 'email']);In addition to prompting the user with simple string prompts, there is a robust API for getting and validating complex information from a command-line prompt. Here's a quick sample:
var schema = {
properties: {
name: {
pattern: /^[a-zA-Z\s\-]+$/,
message: 'Name must be only letters, spaces, or dashes',
required: true
},
password: {
hidden: true
}
}
};
//
// Start the prompt
//
prompt.start();
//
// Get two properties from the user: name, password
//
prompt.get(schema, function (err, result) {
//
// Log the results.
//
console.log('Command-line input received:');
console.log(' name: ' + result.name);
console.log(' password: ' + result.password);
});Pretty easy right? The output from the above script is:
$ node examples/property-prompt.js
prompt: name: nodejitsu000
error: Invalid input for name
error: Name must be only letters, spaces, or dashes
prompt: name: Nodejitsu Inc
prompt: password:
Command-line input received:
name: Nodejitsu Inc
password: some-password
prompt understands JSON-schema with a few extra parameters and uses revalidator for validation.
Here's an overview of the properties that may be used for validation and prompting controls:
{
description: 'Enter your password', // Prompt displayed to the user. If not supplied name will be used.
type: 'string', // Specify the type of input to expect.
pattern: /^\w+$/, // Regular expression that input must be valid against.
message: 'Password must be letters', // Warning message to display if validation fails.
hidden: true, // If true, characters entered will either not be output to console or will be outputed using the `replace` string.
replace: '*', // If `hidden` is set it will replace each hidden character with the specified string.
default: 'lamepassword', // Default value to use if no value is entered.
required: true // If true, value entered must be non-empty.
before: function(value) { return 'v' + value; } // Runs before node-prompt callbacks. It modifies user's input
}Alternatives to pattern include format and conform, as documented in revalidator.
Supported types are string, boolean, number, integer, array
Using type: 'boolean' accepts case insensitive values 'true', 't', 'false', 'f'
Using type: 'array' has some special cases.
descriptionwill not work in the schema iftype: 'array'is defined.maxItemstakes precedence overminItems.- Arrays that do not have
maxItemsdefined will require users toSIGINT(^C) before the array is ended. - If
SIGINT(^C) is triggered beforeminItemsis met, a validation error will appear. This will require users toSIGEOF(^D) to end the input.
For more information on things such as maxItems and minItems, refer to the revalidator repository.
Prompt, in addition to iterating over JSON-Schema properties, will also happily iterate over an array of validation objects given an extra 'name' property:
var prompt = require('../lib/prompt');
//
// Start the prompt
//
prompt.start();
//
// Get two properties from the user: username and password
//
prompt.get([{
name: 'username',
required: true
}, {
name: 'password',
hidden: true,
conform: function (value) {
return true;
}
}], function (err, result) {
//
// Log the results.
//
console.log('Command-line input received:');
console.log(' username: ' + result.username);
console.log(' password: ' + result.password);
});Note that, while this structure is similar to that used by prompt 0.1.x, that the object properties use the same names as in JSON-Schema. prompt 0.2.x is backward compatible with prompt 0.1.x except for asynchronous validation.
Sometimes power users may wish to skip prompts and specify all data as command line options.
if a value is set as a property of prompt.override prompt will use that instead of
prompting the user.
//prompt-override.js
var prompt = require('prompt'),
optimist = require('optimist')
//
// set the overrides
//
prompt.override = optimist.argv
//
// Start the prompt
//
prompt.start();
//
// Get two properties from the user: username and email
//
prompt.get(['username', 'email'], function (err, result) {
//
// Log the results.
//
console.log('Command-line input received:');
console.log(' username: ' + result.username);
console.log(' email: ' + result.email);
})
//: node prompt-override.js --username USER --email EMAILIt is also possible to skip prompts dynamically based on previous prompts.
If an ask method is added, prompt will use it to determine if the prompt should be displayed.
If ask returns true the prompt is displayed. otherwise, the default value or empty string are used.
var schema = {
properties: {
proxy: {
description: 'Proxy url',
},
proxyCredentials: {
description: 'Proxy credentials',
ask: function() {
// only ask for proxy credentials if a proxy was set
return prompt.history('proxy').value > 0;
}
}
}
};
//
// Start the prompt
//
prompt.start();
//
// Get one or two properties from the user, depending on
// what the user answered for proxy
//
prompt.get(schema, function (err, result) {
//
// Log the results.
//
console.log('Command-line input received:');
console.log(' proxy: ' + result.proxy);
console.log(' credentials: ' + result.proxyCredentials);
});A common use-case for prompting users for data from the command-line is to extend or create a configuration object that is passed onto the entry-point method for your CLI tool. prompt exposes a convenience method for doing just this:
var obj = {
password: 'lamepassword',
mindset: 'NY'
}
//
// Log the initial object.
//
console.log('Initial object to be extended:');
console.dir(obj);
//
// Add two properties to the empty object: username and email
//
prompt.addProperties(obj, ['username', 'email'], function (err) {
//
// Log the results.
//
console.log('Updated object received:');
console.dir(obj);
});You can use the prompt.history() method to get access to previous prompt input.
prompt.get([{
name: 'name',
description: 'Your name',
type: 'string',
required: true
}, {
name: 'surname',
description: 'Your surname',
type: 'string',
required: true,
message: 'Please dont use the demo credentials',
conform: function(surname) {
var name = prompt.history('name').value;
return (name !== 'John' || surname !== 'Smith');
}
}], function(err, results) {
console.log(results);
});Aside from changing property.message, you can also change prompt.message
and prompt.delimiter to change the appearance of your prompt.
The basic structure of a prompt is this:
prompt.message + prompt.delimiter + property.message + prompt.delimiter;The default prompt.message is "prompt," the default prompt.delimiter is
": ", and the default property.message is property.name.
Changing these allows you to customize the appearance of your prompts! In
addition, prompt supports ANSI color codes via the
colors module for custom colors. For a
very colorful example:
var prompt = require("prompt");
var colors = require("@colors/colors/safe");
//
// Setting these properties customizes the prompt.
//
prompt.message = colors.rainbow("Question!");
prompt.delimiter = colors.green("><");
prompt.start();
prompt.get({
properties: {
name: {
description: colors.magenta("What is your name?")
}
}
}, function (err, result) {
console.log(colors.cyan("You said your name is: " + result.name));
});If you don't want colors, you can set
var prompt = require('prompt');
prompt.colors = false;When integrating prompt with projects using streamlinejs such as the following
prompt.start();
function test_prompt(_){
console.log(prompt.get(loadDataValues(), _).output);
}
test_prompt(_);
This will work, however the process is then stuck with a stdin stream still open. If you setup the traditional way (with callback) such as this
prompt.start();
function test_prompt(){
prompt.get(loadDataValues(), function(err, data){
console.log(data.output);
});
}
test_prompt();
This works and ends correctly.
To resolve this we have added a new method to prompt, which will stop the stdin stream
//
// ### function stop ()
// Stops input coming in from stdin
//
prompt.stop = function () {
if (prompt.stopped || !prompt.started) {
return;
}
stdin.destroy();
prompt.emit('stop');
prompt.stopped = true;
prompt.started = false;
prompt.paused = false;
return prompt;
}
And you can find an example in the example folder examples/prompt-streamline.js
/*
* prompt-streamline._js: Example of how to use prompt with streamlinejs.
*
* calling syntax: _node prompt-streamline._js
*
*/
var prompt = require('../lib/prompt');
function getSampleData(){
return [
{
name: 'username',
message: 'Enter a username'
}
];
};
//
// Start the prompt
//
prompt.start();
function get_username_prompt(_){
console.log(prompt.get(getSampleData(), _).username);
}
get_username_prompt(_);
//
// Clean the prompt
//
prompt.stop();
By default, prompt prompt binds a process-killing event handler to the SIGINT event (CTRL+C). This allows easily exiting from prompts, but can prevent an app from executing other event handlers when an interrupt is received. In order to override this default behavior, pass a {noHandleSIGINT: true} option into prompt.start.
//
// Disable prompt's built-in SIGINT handling:
//
prompt.start({noHandleSIGINT: true});
process.on('SIGINT', function() {
console.log("This will execute when you hit CTRL+C");
process.exit();
}); $ [sudo] npm install prompt $ npm test
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