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.

Framework Support

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.

With React

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 Storybook')}
  </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>);
});

With Angular

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

import { Button } from '@storybook/angular/demo';

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

// "withKnobs" decorator should be applied before the stories using knobs
stories.addDecorator(withKnobs);

// Knobs for Angular props
stories.add('with a button', () => ({
  component: Button,
  props: {
   text: text('text', 'Hello Storybook'), // The first param of the knob function has to be exactly the same as the component input.
  },
}));

Categorize your knobs by assigning them a groupId. When a groupId exists, tabs will appear in the knobs storybook panel to filter between the groups. Knobs without a groupId are automatically categorized into the ALL group.

// Knob assigned a groupId.
stories.add('as dynamic variables', () => {
  const groupId = 'GROUP-ID1'
  const name = text('Name', 'Arunoda Susiripala', groupId);

  const content = `My name is ${name}.`;
  return (<div>{content}</div>);
});

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

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 groupId = 'GROUP-ID1';

const value = text(label, defaultValue, groupId);

boolean

Allows you to get a boolean value from the user.

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

const label = 'Agree?';
const defaultValue = false;
const groupId = 'GROUP-ID1';

const value = boolean(label, defaultValue, groupId);

number

Allows you to get a number from the user.

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

const label = 'Age';
const defaultValue = 78;
const groupId = 'GROUP-ID1';

const value = number(label, defaultValue);

For use with groupId, pass the default options as the third argument

const value = number(label, defaultValue, {}, groupId);

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 groupId = 'GROUP-ID1';

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

color

Allows you to get a colour from the user.

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

const label = 'Color';
const defaultValue = '#ff00ff';
const groupId = 'GROUP-ID1';

const value = color(label, defaultValue, groupId);

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 groupId = 'GROUP-ID1';

const value = object(label, defaultValue, groupId);

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 groupId = 'GROUP-ID1';

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);

For use with groupId, pass the default separator as the third argument

const value = array(label, defaultValue, ',', groupId);

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',
  Rainbow: ['red', 'orange', 'etc'],
  None: null,
};
const defaultValue = 'red';
const groupId = 'GROUP-ID1';

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

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

files

Allows you to get a value from a file input from the user.

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

const label = 'Images';
const defaultValue = [];

const value = files(label, accept, defaultValue);

Multiple files can be selected, and will be returned as an array of Data URLs

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 groupId = 'GROUP-ID1';

const value = date(label, defaultValue, groupId);

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');
const groupId = 'GROUP-ID1';

button(label, handler, groupId);

withKnobs options

withKnobs also accepts two optional options as story parameters. Usage:

import { storiesOf } from '@storybook/react';
import { withKnobs } from '@storybook/addon-knobs';

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

stories.addDecorator(withKnobs)
stories.add('story name', () => ..., {
  knobs: {
    timestamps: true, // Doesn't emit events while user is typing.
    escapeHTML: true // Escapes strings to be safe for inserting as innerHTML. This option is true by default in storybook for Vue, Angular, and Polymer, because those frameworks allow rendering plain HTML.
                     // You can still set it to false, but it's strongly unrecommendend in cases when you host your storybook on some route of your main site or web app.  
  }
});

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.