Save a web page/selection as an eBook (.epub format) - a Chrome/Firefox/Opera Web Extension

or manually (tested on v. 52.0.2743.116)

1. Navigate to chrome://extensions/
2. Load unpacked extension ...
3. Select the extension's directory

or manually (tested on v. 50.0a2)

1. Navigate to about:debugging
2. Load temporary add-on ...
3. Select the extension's directory

1. Navigate to opera:extensions
2. Load unpacked extension ...
3. Select the extension's directory

sudo apt-get install calibre
ebook-convert "book.epub" "book.mobi"

NOTE These shortcuts are not fixed and the browser will assign a different shortcut if the default one is taken

in Chrome:

1. Navigate to chrome://extensions/
2. Scroll down
3. Click on Keyboard shortcuts

• Added MIME type to the generated .epub file

• Remove unnecessary permissions
• Detect image type if the URL doesn't have a file extension (jpg, gif, png)
• Reset the Busy indicator on errors
• Remove hidden elements when style is not included
• Replace iframes with divs

• Smaller ebook file size
• Fix for #37 - custom styles not applied
• Fix for #36 - br tag missing from pre blocks
• Fix for #31 - hanging in Busy state
• Other misc bug fixes

• Fix for MathML - the rendered expression is too large (Issue #26)
• Add translation in Russian (thanks to @ Emil Khalikov) & Brazilian Portuguese (thanks to @welksonramos)

• Keyboard shortcuts
• Simplified tool bar menu
• Misc bug fixes

• fixed & & issue in title; Issue # 10

• support for hr/br html tags

• BETA: Support for CSS
• BETA: Create / edit custom Styles
• No errors from EPUB Validator (http://validator.idpf.org/) + this should fix the Google Play upload issue

• Chapter Editor: option to save changes
• Chapter Editor: option to remove all chapters
• persist Chapter Editor changes & chapters after generating an eBook or after a browser restart

• make the Custom Style Editor more user friendly
• support backup / restore for Custom Styles
• DONE fix all 'epubcheck' errors (https://github.com/IDPF/epubcheck)
• clean & optimize code
• create tests
• support other formats (mobi, pdf etc.)
• show confirmations (ui/ux)
• display errors (ui/ux)
• DONE support custom style
• add 'remove from ebook' right click menu action

cd tests
yarn install  # install puppeteer
node test/index.js  # should start a chrome instance with Save as eBook loaded

# it will generate and save the ebook in ./tmp-downloads

.... 

• http://ebooks.stackexchange.com/questions/1183/what-is-the-minimum-required-content-for-a-valid-epub
• https://github.com/blowsie/Pure-JavaScript-HTML5-Parser
• https://stuk.github.io/jszip/
• http://johnny.github.io/jquery-sortable/
• https://github.com/eligrey/FileSaver.js/
• https://www.iconfinder.com/icons/753890/book_books_education_library_study_icon#size=128
• Thanks to pumpk0n and Francois Bocquet for helping me with the French translation