WordScooper: Extend selection with keyboard per Christian Bläul

Selecting text with the mouse is fiddly: you overshoot, miss the first letter, or grab half a line too much. WordScooper adds one keyboard shortcut that grows the selection step by step:

word → sentence → paragraph → whole text

Put the cursor anywhere in a word (or select a few words) and press Alt+Shift+. (period), or ⌘⇧Space (Command+Shift+Space) on a Mac. Press it again to grow the selection further. It works in text fields, text areas, editable areas such as e-mail editors, and ordinary page text.

Try it in one minute (on a Mac, press ⌘⇧Space (Command+Shift+Space) wherever it says Alt+Shift+.):

On ordinary page text:
1. Open the Wikipedia article on ice cream: https://en.wikipedia.org/wiki/Ice_cream
2. In the first paragraph of the article, double-click a word that isn't a link (not blue). Your browser selects that word.
3. Press Alt+Shift+. (period). The selection grows to the whole sentence around that word.
4. Press Alt+Shift+. again. The selection grows to the whole paragraph.
5. Keep pressing. The selection grows to ever larger parts of the page, up to the whole article.
6. Press Ctrl+C (Cmd+C on a Mac) to copy what you selected, or click anywhere to start over.

In a text field:
1. On the same page, click the Wikipedia search box at the top and type: Ice cream is cold. It tastes sweet.
2. Click into the middle of the word "tastes", so the text cursor blinks inside it. Nothing is selected yet.
3. Press Alt+Shift+. The word "tastes" is selected.
4. Press Alt+Shift+. again. "It tastes sweet." is selected.
5. Press Alt+Shift+. once more. All of the text in the search box is selected.

Nothing happens? Make sure the browser window is active and you aren't on a browser page such as the new-tab page or the add-on store. There, browsers don't allow extensions to run. If another program uses the same shortcut, pick a different one (see "Change the shortcut" below).

Languages: word and sentence boundaries come from the browser's built-in language rules, so German, French, Spanish and many other languages work, not just English.

Change the shortcut: choose a combination that doesn't type a character. On a Mac, make sure to include command or control in your combination.
Open about:addons, click the gear icon, then "Manage Extension Shortcuts"

Privacy: WordScooper only runs on a page when you press its shortcut. It can't read your pages otherwise, stores nothing and sends nothing anywhere.

Limitations: it doesn't work on the browser's own pages or the add-on stores, or inside embedded frames from other websites.

Source code (GPL-3.0): https://github.com/WordScooper/WordScooper-browser-extension