## Usage

```js
var askWhen = require('ask-when');
var questions = require('base-questions');
var Base = require('base');
var app = new Base({isApp: true});

// register plugins
app.use(questions());
app.use(askWhen());
```

## API

### askWhen

The main export is a function that can be passed to `.use()`, if you want to register this as a plugin.

```js
app.askWhen(name, options, cb);
```

**Params**

- `name` **{String}**: question name
- `options` **{Object|Function}**: Callback, or options object. If options, an "answer" value may be passed on `options[name]`.
- `cb` **{Function}**: callback


**Prerequisites**

- [base-questions][]: the `base-questions` plugin must be registered before `ask-when` is registered
- `isApp` must be defined on the instance (either define `app.isApp = true`, or pass `{isApp: true}` to the constructor. This prevents the plugin from loading on [invalid instances](https://github.com/node-base/is-valid-app)):

**Register the plugin**

```js
var askWhen = require('{%= name %}');
var questions = require('base-questions');
var Base = require('base');
var app = new Base({isApp: true});

// register plugins
app.use(questions());
app.use(askWhen());
```

**Example usage**

```js
// define when
app.options.askWhen = 'not-answered';

app.question('dest', 'Destination directory?', {default: process.cwd()})
  .askWhen('dest', function(err, answers) {
    if (err) return console.log(err);
    console.log(answers)
  });
```

### .when

Alternatively, a `.when` method is exposed if you don't want to register this as a plugin.

```js
ask.when(app, name, val, cb);
```

**Params**

- `app` **{Object}**: instance of [base][] (one of the applications listed in the [compatibility section](#compatibility))
- `name` **{String}**: question name
- `options` **{Object|Function}**: Callback, or options object. If options, an "answer" value may be passed on `options[name]`.
- `cb` **{Function}**: callback

**Prerequisites**

- [base-questions][]: the `base-questions` plugin must be registered before `ask-when` is registered


```js
var ask = require('{%= name %}');
var askWhen = require('{%= name %}');
var questions = require('base-questions');
var Base = require('base');
var app = new Base({isApp: true});

// register the `base-questions` plugin first
app.use(questions());

// ask questions
app.question('dest', 'Destination directory?', {default: process.cwd()})
ask.when(app, 'dest', function(err, answers) {
  if (err) return console.log(err);
  console.log(answers)
});
```

### Options

This library wraps the `.ask` method from [base-questions][] to allow prompts to be conditionally skipped when one of the following values is defined on `options` (either on `app.options`, or options passed to `askWhen` directly)

- `never`: the question will always be skipped
- `always`: the question will always be asked
- `not-answered`: the question will only be asked if a value is not already defined

## Compatibility

Can be used with any of the following libs:

* [question-cache][]
* [question-store][]
* [base][], when the [base-questions][] plugin is used
* [assemble][], in your `assemblefile.js`
* [generate][], in your `generator.js`
* [update][], in your `updatefile.js`
* [verb][], in your `verbfile.js`