knobs

Storybook Addon Knobs

---

Storybook Addon Knobs allow you to edit React props dynamically using the Storybook UI. You can also use Knobs as a dynamic variable inside stories in Storybook.

This addon works with Storybook for:

• React
• React Native
• Vue

This is how Knobs look like:

Checkout the above Live Storybook or watch this video.

Getting Started

First of all, you need to install knobs into your project as a dev dependency.

npm install @storybook/addon-knobs --save-dev

Then, configure it as an addon by adding it to your addons.js file (located in the Storybook config directory).

import '@storybook/addon-knobs/register'

Now, write your stories with knobs.

import { storiesOf } from '@storybook/react';
import { withKnobs, text, boolean, number } from '@storybook/addon-knobs';

const stories = storiesOf('Storybook Knobs', module);

// Add the `withKnobs` decorator to add knobs support to your stories.
// You can also configure `withKnobs` as a global decorator.
stories.addDecorator(withKnobs);

// Knobs for React props
stories.add('with a button', () => (
  <button disabled={boolean('Disabled', false)} >
    {text('Label', 'Hello Button')}
  </button>
))

// Knobs as dynamic variables.
stories.add('as dynamic variables', () => {
  const name = text('Name', 'Arunoda Susiripala');
  const age = number('Age', 89);

  const content = `I am ${name} and I'm ${age} years old.`;
  return (<div>{content}</div>);
});

You can see your Knobs in a Storybook panel as shown below.

Additional Links

• Introduction blog post.
• Watch this video on how to use knobs
• Live Storybook with Knobs
• Have a look at this sample Storybook repo.

Available Knobs

These are the knobs available for you to use. You can import these Knobs from the @storybook/addon-knobs module. Here's how to import the text Knob.

import { text } from '@storybook/addon-knobs';

Just like that, you can import any other following Knobs:

text

Allows you to get some text from the user.

import { text } from '@storybook/addon-knobs';

const label = 'Your Name';
const defaultValue = 'Arunoda Susiripala';

const value = text(label, defaultValue);

boolean

Allows you to get a boolean value from the user.

import { boolean } from '@storybook/addon-knobs';

const label = 'Agree?';
const defaultValue = false;

const value = boolean(label, defaultValue);

number

Allows you to get a number from the user.

import { number } from '@storybook/addon-knobs';

const label = 'Age';
const defaultValue = 78;

const value = number(label, defaultValue);

number bound by range

Allows you to get a number from the user using a range slider.

import { number } from '@storybook/addon-knobs';

const label = 'Temperature';
const defaultValue = 73;
const options = {
   range: true,
   min: 60,
   max: 90,
   step: 1,
};

const value = number(label, defaultValue, options);

color

Allows you to get a colour from the user.

import { color } from '@storybook/addon-knobs';

const label = 'Color';
const defaultValue = '#ff00ff';

const value = color(label, defaultValue);

object

Allows you to get a JSON object or array from the user.

import { object } from '@storybook/addon-knobs';

const label = 'Styles';
const defaultValue = {
  backgroundColor: 'red'
};

const value = object(label, defaultValue);

Make sure to enter valid JSON syntax while editing values inside the knob.

array

Allows you to get an array of strings from the user.

import { array } from '@storybook/addon-knobs';

const label = 'Styles';
const defaultValue = ['Red']

const value = array(label, defaultValue);

While editing values inside the knob, you will need to use a separator. By default it's a comma, but this can be override by passing a separator variable.

import { array } from '@storybook/addon-knobs';

const label = 'Styles';
const defaultValue = ['Red'];
const separator = ':';
const value = array(label, defaultValue, separator);

select

Allows you to get a value from a select box from the user.

import { select } from '@storybook/addon-knobs';

const label = 'Colors';
const options = {
  red: 'Red',
  blue: 'Blue',
  yellow: 'Yellow',
};
const defaultValue = 'red';

const value = select(label, options, defaultValue);

You can also provide options as an array like this: ['red', 'blue', 'yellow']

date

Allow you to get date (and time) from the user.

import { date } from '@storybook/addon-knobs';

const label = 'Event Date';
const defaultValue = new Date('Jan 20 2017');
const value = date(label, defaultValue);

Note: the default value must not change - e.g., do not do date('Label', new Date()) or date('Label')

The date knob returns the selected date as stringified Unix timestamp (e.g. "1510913096516"). If your component needs the date in a different form you can wrap the date function:

function myDateKnob(name, defaultValue) {
  const stringTimestamp = date(name, defaultValue)
  return new Date(stringTimestamp)
}

button

Allows you to include a button and associated handler.

import { button } from '@storybook/addon-knobs';

const label = 'Do Something';
const handler = () => doSomething('foobar');
button(label, handler);

withKnobs vs withKnobsOptions

If you feel like this addon is not performing well enough there is an option to use withKnobsOptions instead of withKnobs. Usage:

story.addDecorator(withKnobsOptions({
  debounce: { wait: number, leading: boolean}, // Same as lodash debounce.
  timestamps: true // Doesn't emit events while user is typing.
}));

Typescript

If you are using typescript, make sure you have the type definitions installed for the following libs:

• node
• react

You can install them using npm install -save @types/node @types/react, assuming you are using Typescript >2.0.