Vocab：translate highlighted text and record the translation in a glossary book..
Allow user to specify a CSS selector, if glossary card is enabled in settings, random card will also show up when user clicks that CSS selector element (if it indeed exists on the webpage)
Translate selected text on context menu.
Translation will be shown and can also be added to a glossary notebook by clicking ‘+’ button
View the vocabularies in extension popover
The vocabularies can also be edited, exported/imported and read aloud repeatedly
Set the language source and target in extension popover
The translation is achieved by google translation free API.