Due to the way turndown pads every block element with 2 new lines, and
makes `br` double space by default, we would get 3 blank lines pasted
when there's just 1 line break between 2 paragraphs.
Now we set `br` to an empty string, and since turndown collapses
sequences of multiple new lines to `\n\n` (1 blank line), so any 2 block
elements will now always have 1 blank line between them, irrespective of
if and how many line breaks there are between them in the copied HTML.
Turndown would strip `<style>` tags, but retain the content enclosed.
This resulted in unwanted content being pasted, like the comment nodes
inside the `<style>` tag when pasting cell/s copied from Google Sheets.
If the selection copied, is entirely within a single element, like text
within a heading (like `h1`) we discard this outermost element and only
convert the inner HTML to markdown.
However, we retain `pre` so a code block within it stays as is and does
not change into inline code, losing all its linebreaks.
Turned off and tested escaping with `/` (for now).
Added support + tests for:
- headings.
- strikethrough.
- nested lists.
- code blocks.
Improved handling of:
- links (custom and raw, ignored when wrapping a single image).
- images (now pasted in Zulip's link like syntax).
- custom emojis.
- LaTeX (no garbage symbols, unformatted plain text is pasted)
Added tests for emojis.
Known concerns:
- External images aren't handled anymore by upload.js -- is this a bug?
- Tables lose their formatting on paste.
This lets us simplify the long-ish ‘../../static/js’ paths, and will
remove the need for the ‘zrequire’ wrapper.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
N-Shar-ma
Karl Stolley
Anders Kaseorg