francoischalifour/medium-zoom

medium-zoom

A JavaScript library for zooming images like Medium

🔬 Playground ・ 🔎 Demo ・ 📚 Storybook

Features

• 📱 Responsive — scale on mobile and desktop
• 🚀 Performant and lightweight — optimized to reach 60 fps
• ⚡️ High definition support — load the HD version of your image on zoom
• 🔎 Flexibility — apply the zoom to a selection of images
• 🖱 Mouse, keyboard and gesture friendly — click anywhere, press a key or scroll away to close the zoom
• 🎂 Event handling — trigger events when the zoom enters a new state
• 📦 Customization — set your own margin, background and scroll offset
• 🔧 Pluggable — add your own features to the zoom
• 💎 Custom templates — extend the default look to match the UI of your app
• 🔌 Framework agnostic — works with React, Vue, Angular, Svelte, Solid, etc.

Installation

The module is available on the npm registry.

npm install medium-zoom
# or
yarn add medium-zoom

Download

• Normal
• Minified

CDN

• jsDelivr
• unpkg

Usage

Try it out in the browser

Import the library as a module:

import mediumZoom from 'medium-zoom'

Or import the library with a script tag:

<script src="node_modules/medium-zoom/dist/medium-zoom.min.js"></script>

That's it! You don't need to import any CSS styles.

Assuming you add the data-zoomable attribute to your images:

mediumZoom('[data-zoomable]')

API

mediumZoom(selector?: string | HTMLElement | HTMLElement[] | NodeList, options?: object): Zoom

Selectors

The selector allows attaching images to the zoom. It can be of the following types:

• CSS selectors
• HTMLElement
• NodeList
• Array

// CSS selector
mediumZoom('[data-zoomable]')

// HTMLElement
mediumZoom(document.querySelector('#cover'))

// NodeList
mediumZoom(document.querySelectorAll('[data-zoomable]'))

// Array
const images = [
  document.querySelector('#cover'),
  ...document.querySelectorAll('[data-zoomable]'),
]

mediumZoom(images)

Options

The options enable the customization of the zoom. They are defined as an object with the following properties:

mediumZoom('[data-zoomable]', {
  margin: 24,
  background: '#BADA55',
  scrollOffset: 0,
  container: '#zoom-container',
  template: '#zoom-template',
})

Methods

open({ target?: HTMLElement }): Promise<Zoom>

Opens the zoom and returns a promise resolving with the zoom.

const zoom = mediumZoom('[data-zoomable]')

zoom.open()

Emits an event open on animation start and opened when completed.

close(): Promise<Zoom>

Closes the zoom and returns a promise resolving with the zoom.

const zoom = mediumZoom('[data-zoomable]')

zoom.close()

Emits an event close on animation start and closed when completed.

toggle({ target?: HTMLElement }): Promise<Zoom>

Opens the zoom when closed / dismisses the zoom when opened, and returns a promise resolving with the zoom.

const zoom = mediumZoom('[data-zoomable]')

zoom.toggle()

attach(...selectors: string[] | HTMLElement[] | NodeList[] | Array[]): Zoom

Attaches the images to the zoom and returns the zoom.

const zoom = mediumZoom()

zoom.attach('#image-1', '#image-2')
zoom.attach(
  document.querySelector('#image-3'),
  document.querySelectorAll('[data-zoomable]')
)

detach(...selectors: string[] | HTMLElement[] | NodeList[] | Array[]): Zoom

Releases the images from the zoom and returns the zoom.

const zoom = mediumZoom('[data-zoomable]')

zoom.detach('#image-1', document.querySelector('#image-2')) // detach two images
zoom.detach() // detach all images

Emits an event detach on the image.

update(options: object): Zoom

Updates the options and returns the zoom.

const zoom = mediumZoom('[data-zoomable]')

zoom.update({ background: '#BADA55' })

Emits an event update on each image of the zoom.

clone(options?: object): Zoom

Clones the zoom with provided options merged with the current ones and returns the zoom.

const zoom = mediumZoom('[data-zoomable]', { background: '#BADA55' })

const clonedZoom = zoom.clone({ margin: 48 })

clonedZoom.getOptions() // => { background: '#BADA55', margin: 48, ... }

on(type: string, listener: () => void, options?: boolean | AddEventListenerOptions): Zoom

Registers the listener on each target of the zoom.

The same options as addEventListener are used.

const zoom = mediumZoom('[data-zoomable]')

zoom.on('closed', event => {
  // the image has been closed
})

zoom.on(
  'open',
  event => {
    // the image has been opened (tracked only once)
  },
  { once: true }
)

The zoom object is accessible in event.detail.zoom.

off(type: string, listener: () => void, options?: boolean | AddEventListenerOptions): Zoom

Removes the previously registered listener on each target of the zoom.

The same options as removeEventListener are used.

const zoom = mediumZoom('[data-zoomable]')

function listener(event) {
  // ...
}

zoom.on('open', listener)
// ...
zoom.off('open', listener)

The zoom object is accessible in event.detail.zoom.

getOptions(): object

Returns the zoom options as an object.

const zoom = mediumZoom({ background: '#BADA55' })

zoom.getOptions() // => { background: '#BADA55', ... }

getImages(): HTMLElement[]

Returns the images attached to the zoom as an array of HTMLElements.

const zoom = mediumZoom('[data-zoomable]')

zoom.getImages() // => [HTMLElement, HTMLElement]

getZoomedImage(): HTMLElement

Returns the current zoomed image as an HTMLElement or null if none.

const zoom = mediumZoom('[data-zoomable]')

zoom.getZoomedImage() // => null
zoom.open().then(() => {
  zoom.getZoomedImage() // => HTMLElement
})

Attributes

data-zoom-src

Specifies the high definition image to open on zoom. This image loads when the user clicks on the source image.

<img src="image-thumbnail.jpg" data-zoom-src="image-hd.jpg" alt="My image" />

Events

const zoom = mediumZoom('[data-zoomable]')

zoom.on('open', event => {
  // track when the image is zoomed
})

The zoom object is accessible in event.detail.zoom.

Framework integrations

Medium Zoom is a JavaScript library that can be used with any framework. Here are some integrations that you can use to get started quickly:

• React
• React Markdown
• Vue
• Svelte

Examples

const button = document.querySelector('[data-action="zoom"]')
const zoom = mediumZoom('#image')

button.addEventListener('click', () => zoom.open())

let counter = 0
const zoom = mediumZoom('#image-tracked')

zoom.on('open', event => {
  console.log(`"${event.target.alt}" has been zoomed ${++counter} times`)
})

const zoom = mediumZoom('[data-zoomable]')

zoom.on('closed', () => zoom.detach(), { once: true })

mediumZoom($('[data-zoomable]').toArray())

import React, { useRef } from 'react'
import mediumZoom from 'medium-zoom'

export function ImageZoom({ options, ...props }) {
  const zoomRef = useRef(null)

  function getZoom() {
    if (zoomRef.current === null) {
      zoomRef.current = mediumZoom(options)
    }

    return zoomRef.current
  }

  function attachZoom(image) {
    const zoom = getZoom()

    if (image) {
      zoom.attach(image)
    } else {
      zoom.detach()
    }
  }

  return <img {...props} ref={attachZoom} />
}

You can see more examples including React and Vue, or check out the storybook.

Debugging

The zoomed image is not visible

The library doesn't provide a z-index value on the zoomed image to avoid conflicts with other frameworks. Some frameworks might specify a z-index for their elements, which makes the zoomed image not visible.

If that's the case, you can provide a z-index value in your CSS:

.medium-zoom-overlay,
.medium-zoom-image--opened {
  z-index: 999;
}

Browser support

^* These browsers require a template polyfill when using custom templates.

Cross-browser testing is sponsored by

Contributing

• Run yarn to install Node dev dependencies
• Run yarn start to build the library in watch mode
• Run yarn run storybook to see your changes at http://localhost:9001

Please read the contributing guidelines for more detailed explanations.

You can also use npm.

License

MIT © François Chalifour