React Reader - an easy way to embed a ePub into your webapp
An ePub-reader for react powered by EpubJS #react #epubjs #webpack #babel #standardjs
React wrapper for EpubJS
React Reader is a react-wrapper for epub.js using the v.03 branch.
About
epub.js is a great library and this is a wrapper for it. This wrapper makes it easy to use in a React-app.
This package publish 4 named exports:
- ReactReader - Most used, a basic epub-reader to embed into your webapp
- ReactReaderStyle - styles for above if you need to overwrite them, see the file
- EpubView - Underlaying epub-canvas (wrapper for epub.js iframe)
- EpubViewStyle - styles for above if you need to overwrite them, see the file
Also note that EpubJS is a browser-based epub-reader and it works by rendering the current epub-chapter into an iframe, and then by css-columns it will display the current page. See limitations below
Basic usage
npm install react-reader --save
-or-
yarn add react-reader
And in your react-component...
import React, { useState } from "react"
import { ReactReader } from "react-reader"
const App = () => {
// And your own state logic to persist state
const [location, setLocation] = useState(null)
const locationChanged = (epubcifi) => {
// epubcifi is a internal string used by epubjs to point to a location in an epub. It looks like this: epubcfi(/6/6[titlepage]!/4/2/12[pgepubid00003]/3:0)
setLocation(epubcifi)
}
return (
<div style={{ height: "100vh" }}>
<ReactReader
location={location}
locationChanged={locationChanged}
url="https://react-reader.metabits.no/files/alice.epub"
/>
</div>
)
}
export default App
ReactReader props
title
[string] - the title of the book, displayed above the reading-canvasshowToc
[bool] - whether to show the toc / toc-navstyles
[object] - override the default stylesepubViewStyles
[object] - override the default styles for inner EpubViewswipeable
[bool, default false] - enable swiping left/right with react-swipeable. Warning this will disable interacting with epub.js iframe content like selection
ReactReader props passed to inner EpubView
url
[string, required] - url to the epub-file, if its on another domain, remember to add cors for the file. Epubjs fetch this by a http-call, so it need to be public available.loadingView
[element] - if you want to customize the loadingViewlocation
[string, number] - set / update location of the epublocationChanged
[func] - a function that receives the current location while user is reading. This function is called everytime the page changes, and also when it first renders.tocChanged
[func] - when the reader has parsed the book you will receive an array of the chaptersepubInitOptions
[object] - pass custom properties to the epub init function, see epub.jsepubOptions
[object] - pass custom properties to the epub rendition, see epub.js's book.renderTo functiongetRendition
[func] - when epubjs has rendered the epub-file you can get access to the epubjs-rendition object here
EpubView props
EpubView
is just the iframe-view from EpubJS if you would like to build the reader yourself, see above for props
Recipes and tips
TypeScript support
See also TypeScript definition for React Reader here (thanks to @rafaelsaback)
Can community supply an example of this
Save and retrieve progress from storage
Saving the current page on storage is pretty simple, but we need to keep in mind that locationChanged
also gets called on the very
first render of our app.
import React, { useState, useRef } from "react"
import { ReactReader } from "react-reader"
const App = () => {
// And your own state logic to persist state
const [location, setLocation] = useState(null)
const [firstRenderDone, setFirstRenderDone] = useState(false)
const renditionRef = useRef(null)
const locationChanged = (epubcifi) => {
// Since this function is also called on initial rendering, we are using custom state
// logic to check if this is the initial render.
// If you block this function from running (i.e not letting it change the page on the first render) your app crashes.
if (!firstRenderDone){
setLocation(localStorage.getItem("book-progress")) // getItem returns null if the item is not found.
setFirstRenderDone(true)
return;
}
// This is the code that runs everytime the page changes, after the initial render.
// Saving the current epubcifi on storage...
localStorage.setItem("book-progress", epubcifi)
// And then rendering it.
setLocation(epubcifi) // Or setLocation(localStorage.getItem("book-progress"))
}
return (
<div style={{ height: "100vh" }}>
<ReactReader
location={location}
locationChanged={locationChanged}
url="https://react-reader.metabits.no/files/alice.epub"
getRendition={(rendition) => renditionRef.current = rendition}
/>
</div>
)
}
export default App
Why not use useEffect
for this?
Because the locationChanged
function would overwrite the useEffect
changes,
and if we block it from running on initial rendering the book doesn't render.
Overwrite styles with react-styles
Import the published styles and extend them, or you can wrap it in a custom container where you can overwrite styles by nested css-styles
import React from "react"
import {
ReactReader,
ReactReaderStyle
} from "react-reader"
const ownStyles = {
...ReactReaderStyle,
arrow: {
...ReactReaderStyle.arrow,
color: 'red'
}
}
const App = () => {
return (
<div style={{ height: "100vh" }} className="myReader">
<ReactReader
url="https://react-reader.metabits.no/files/alice.epub"
styles={ownStyles}
/>
</div>
)
}
Display page number for current chapter
We store the epubjs rendition in a ref, and get the page numbers in the callback when location is changed. Note that in this example we also find them name of the current chapter from the toc. Also see limitation for pagination for the whole book.
import React, { useRef, useState } from "react"
import { ReactReader } from "react-reader"
const App = () => {
const [page, setPage] = useState('')
const renditionRef = useRef(null)
const tocRef = useRef(null)
const locationChanged = (epubcifi) => {
if (renditionRef.current && tocRef.current) {
const { displayed, href } = renditionRef.current.location.start
const chapter = tocRef.current.find((item) => item.href === href)
setPage(`Page ${displayed.page} of ${displayed.total} in chapter ${chapter ? chapter.label : 'n/a'}`)
}
}
return (
<>
<div style={{ height: "100vh" }}>
<ReactReader
locationChanged={locationChanged}
url="https://react-reader.metabits.no/files/alice.epub"
getRendition={(rendition) => renditionRef.current = rendition}
tocChanged={toc => tocRef.current = toc}
/>
</div>
<div style={{ position: 'absolute', bottom: '1rem', right: '1rem', left: '1rem', textAlign: 'center', zIndex: 1}}>
{page}
</div>
</>
)
}
Change font-size
Hooking into epubJS rendition object is the key for this also.
import React, { useRef, useState, useEffect } from "react"
import { ReactReader } from "react-reader"
const App = () => {
const [size, setSize] = useState(100)
const renditionRef = useRef(null)
const changeSize = (newSize) => {
setSize(newSize)
}
useEffect(() => {
if (renditionRef.current) {
renditionRef.current.themes.fontSize(`${size}%`)
}
}, [size])
return (
<>
<div style={{ height: "100vh" }}>
<ReactReader
url="https://react-reader.metabits.no/files/alice.epub"
getRendition={(rendition) => {
renditionRef.current = rendition
renditionRef.current.themes.fontSize(`${size}%`)
}}
/>
</div>
<div style={{ position: 'absolute', bottom: '1rem', right: '1rem', left: '1rem', textAlign: 'center', zIndex: 1}}>
<button onClick={() => changeSize(Math.max(80, size - 10))}>-</button>
<span>Current size: {size}%</span>
<button onClick={() => changeSize(Math.min(130, size + 10))}>+</button>
</div>
</>
)
}
Add / adjust custom css for the epub-html
EpubJS render the epub-file inside a iframe so you will need to create a custom theme and apply it.
This is useful for when you want to set custom font families, custom background and text colors, and everything CSS related.
import React from "react"
import { ReactReader } from "react-reader"
const App = () => {
return (
<div style={{ height: "100vh" }}>
<ReactReader
url="https://react-reader.metabits.no/files/alice.epub"
getRendition={(rendition) => {
rendition.themes.register('custom', {
"*": {
color: #FFFFFF,
backgroundColor: "#252525",
},
img: {
border: '1px solid red'
},
p: {
'font-family': 'Helvetica, sans-serif',
'font-weight': '400',
'font-size': '20px',
border: '1px solid green'
}
})
rendition.themes.select('custom')
}}
/>
</div>
)
}
Hightlight selection in epub
This shows how to hook into epubJS annotations object and let the user highlight selection and store this in a list where user can go to a selection or delete it.
import React, { useRef, useState, useEffect } from "react"
import { ReactReader } from "react-reader"
const App = () => {
const [selections, setSelections] = useState([])
const renditionRef = useRef(null)
useEffect(() => {
if (renditionRef.current) {
function setRenderSelection(cfiRange, contents) {
setSelections(selections.concat({
text: renditionRef.current.getRange(cfiRange).toString(),
cfiRange
}))
renditionRef.current.annotations.add("highlight", cfiRange, {}, null , "hl", {"fill": "red", "fill-opacity": "0.5", "mix-blend-mode": "multiply"})
contents.window.getSelection().removeAllRanges()
}
renditionRef.current.on("selected", setRenderSelection)
return () => {
renditionRef.current.off("selected", setRenderSelection)
}
}
}, [setSelections, selections])
return (
<>
<div style={{ height: "100vh" }}>
<ReactReader
url="https://react-reader.metabits.no/files/alice.epub"
getRendition={(rendition) => {
renditionRef.current = rendition
renditionRef.current.themes.default({
'::selection': {
'background': 'orange'
}
})
setSelections([])
}}
/>
</div>
<div style={{ position: 'absolute', bottom: '1rem', right: '1rem', zIndex: 1, backgroundColor: 'white'}}>
Selection:
<ul>
{selections.map(({text, cfiRange}, i) => (
<li key={i}>
{text} <button onClick={() => {
renditionRef.current.display(cfiRange)
}}>Show</button>
<button onClick={() => {
renditionRef.current.annotations.remove(cfiRange, 'highlight')
setSelections(selections.filter((item, j) => j !== i))
}}>x</button>
</li>
))}
</ul>
</div>
</>
)
}
Handling missing mime-types on server
EpubJS will try to parse the epub-file you pass to it, but if the server send wrong mine-types or the file does not contain .epub
you can use the epubInitOptions prop to force reading it right.
import React from "react"
import { ReactReader } from "react-reader"
const App = () => {
return (
<div style={{ height: "100vh" }}>
<ReactReader
url="/my-epub-service"
epubInitOptions={{
openAs: 'epub'
}}
/>
</div>
)
}
Display a scrolled epub-view
Pass options for this into epubJS in the prop epubOptions
import React from "react"
import { ReactReader } from "react-reader"
const App = () => {
return (
<div style={{ height: "100vh" }}>
<ReactReader
url="https://react-reader.metabits.no/files/alice.epub"
epubOptions={{
flow: "scrolled",
manager: "continuous"
}}
/>
</div>
)
}
Quick reference for manager and flow options:
enum ManagerOptions {
default = "default", // Default setting, use when flow is set to auto/paginated.
continuous = "continuous", // Renders stuff offscreen, use when flow is set to "scrolled".
}
enum FlowOptions {
default = "auto", // Based on OPF settings, defaults to "paginated"
paginated = "paginated", // Left to right, paginated rendering. Better paired with the default manager.
scrolled = "scrolled", // Scrolled viewing, works best with "continuous" manager.
}
Things will look weird if you use the wrong manager/flow combination.
Limitations
EpubJS is a browser-based epub-reader and it works by rendering the current epub-chapter into an iframe, and then by css-columns it will display the current page.
- EpubJS will need to render the current chapter before it will now how many pages it will have in the current viewport. Because of this it will not be able to tell you at which page in the whole epub-book you are at, nor will you be able to get the total pages for the whole book
- Performance for a web-based epub-reader will not be the same as native readers.
- EpubJS support
epub 2
standard, but mostepub 3
features should work since its based on regular html-tags, but there can be more issues with those See Epub on Wikipedia
Also be aware that the epub-standard is basically a zip of html-files, and there is a range in quality. Most publishers create pretty ok epubs, but in some older books there could be errors that will make rendering fails.
Handling not valid epub-files
A tip if you have problems with not valid epub-files is to override the build in DOMParser and modify the markup-string passed to its parseFromString function. This example fixes a not valid <title/>
tag in an old epub, which would render as a blank page if not fixed:
const DOMParser = window.DOMParser
class OwnParser {
parseFromString(markup, mime) {
if (markup.indexOf('<title/>') !== -1) {
markup = markup.replace('<title/>', '');
}
return new DOMParser().parseFromString(markup, mime)
}
}
window.DOMParser = OwnParser