paste-html-to-govspeak: Functionality overview
The paste HTML to govspeak functionality interfaces with data on a user's clipboard to attempt to create govspeak formatted text at the point of them pasting HTML. The expectation for usage is that users copy data from word processor documents (such as Microsoft Word or Google Docs), fixed layout documents (such as PDF) or webpage content and paste it into the tool.
The quality and accuracy of clipboard data can vary significantly depending on the type of document it is copied from and what program is used to open it. This means that outcomes can sometimes be surprising. The goal of the tool is therefore somewhat modest: to consistently provide a paste experience that is at least as good as pasting plain text and to enhance wherever possible.
This document serves to explain more about how this tool works, it's limitations and issues discovered in testing scenarios.
How this tool works
This tools listens for a paste event to occur on a designated element. When this event occurs it uses the ClipboardData API to check whether the paste content is available in a HTML format and, if so, converts this HTML to Govspeak. If HTML is not available it falls back to the browsers default behaviour - which would be to insert or replace the text content of the paste.
As HTML is a widely understood open format it is frequently available as part of clipboard data to allow the communication of rich text between applications. For HTML to be available on a paste event it needs to have been written to the clipboard at the time it was copied. This is something that is done by the application displaying the content and may use features of the underlying operating system. For example, if you copy text in Microsoft Word it will automatically convert this text to HTML (and other formats such as plain text) when placing it on the clipboard.
The conversion of HTML to Govspeak is relatively simple. Elements that can be identified as having a Govspeak equivialent, such as a link, are converted to their equivalent; elements that are used for non visible data, such as style information, are removed; and any other elements are converted to their text representation. This conversion is done by using the turndown package.
In order to produce a good Govspeak conversion the HTML must be marked up semantically. This allows the original author's content intent to be understood by different applications regardless of the formatting. In order for this to occur the author must have specified these semantics when producing their document (for example a user selecting text as a heading) and the application used to read the document must include this information in copy data to the clipboard.
Falling back to text input
When pasting this tool will use HTML data if it is available. In most desktop browsers there is an option to force this to be treated as plain text - which will disable the effects of this tool.
On Windows and Linux machines this can be achieved by using
Ctrl + Shift + v
rather than the usual
Ctrl + v to paste. On macOS the same can be achieved
Cmd + Shift + v.
On some browsers there are also options on the context menu such as "Paste as plain text" on Windows and "Paste and match style" on macOS. These will paste in as plain text, bypassing this tool.
Only a subset of HTML is converted to Govspeak.
Elements that are converted, but with attributes stripped are:
p, h1, h2, h3, h4, h5, blockquote, pre, code, ol, ul, li, br
Note: As GOV.UK only encourages the use of headers of level 2 and 3, h1 elements are converted to level 2 headers whereas h4 and h5 elements are converted to level 3 headers.
Elements that are stripped with allowed attributes are:
a with href, attr with title
Elements that are purposefully stripped for Govspeak consistency, but typically allowed in markdown are:
h6, b, strong, em, i, img
Most other elements (most notably tables) are converted to just show text within them, except for ones that contain non-content data (such as style, script or meta elements) which are removed.
For an example of a best case paste scenario there is an input example file, containing the supported HTML. This can be pasted into the tool example to see the conversion.
Overview of testing outcomes
In preparing to deploy this functionality we tested a wide range of scenarios. The approach to testing was to create a matrix identifying different authoring tools (such as Microsoft Word, Google Docs) and different output formats (such as docx, odt, pdf) which could be opened on different platforms. We then looked at other common sources of content such as web pages or e-mail clients.
We found that saving from tools such as Word or Google Docs to cross platform formats such as ODT or RTF didn't have a significant impact on the formatting of the document. However this did produce some buggy circumstances such as headers embedded in ordered lists.
If a document has content separated with line breaks, these may often be converted into separate paragraphs which creates an additional line break. This happens when the source document stores the separate lines as separate paragraphs.
It is expected that users may copy and paste Govspeak/markdown from example sources that are represented in HTML (for example How to publish on GOV.UK). Because of this no markdown is escaped when it is within HTML. This can impact users who wish to use characters that have a syntactic meaning in Govspeak.
If a document author uses text formatting to create semantic meaning (such as headers or lists) this information won't be retained when converting to Govspeak. This is because the source document is unable to output this with semantic meaning. In some cases (detailed below) some word processing tools will still strip the semantic meaning even if it is present in the document.
Microsoft Word 2016
Testing the authoring and copying of content produced mostly positive results with Word 2016. Headers, paragraphs and most links copied successfully.
Lists are problematic. Word copies these as a sequence of paragraphs with bullet characters preserved, we have a workaround that parses these.
We found that when a document has comments these are included in the content that is copied. This behaviour is different than other word processors such as Google Docs and Libre Office. We have code to remove the comments.
Another identified issue was that automatic links to email addresses weren't
copying as valid links as they missed a
href attribute, for example
<a>email@example.com</a>. These end up being stripped to text in conversion.
Using Google Docs provides two different experiences depending on how the document is opened: editing and previewing.
Editing a document
Copying from the edit interface provided a good copy and pasting experience, with semantic markup copied and converted.
We discovered, and resolved, a couple of issues relating to lists. The first being that list items contained paragraph markup. The second that nested lists appear with invalid HTML.
Previewing a document
When documents are opened using the preview mode in Google Docs a copy does not include a HTML variant so no enhancement is available. Therefore, these paste as if they were plain text.
Office Editing for Docs, Sheets and Slides chrome extension
Google provide this popular chrome extension that allows opening many of the common Microsoft Office formats in the Chrome web browser. These look very similar to Google Docs but behave differently.
The HTML that is copied from this source is less semantic than Google Docs, with most semantic markup (such as headers and lists) converted to paragraphs. Links do seem to be persisted.
We did encounter a strange issue - that may be a problem with the extension - where documents longer than 2 pages didn't copy content past the 2nd page in either HTML or text pasting.
PDF documents mostly copy as only plain text or have minimal HTML available, thus these have little to no Govspeak available when pasted. In some circumstances we found PDF to provide a particularly poor experience by stripping all line breaks or including superfluous characters.
Different PDF readers all seemed to produce different HTML results, with the common theme being a lack of semantic information.
In some cases the HTML paste of a PDF was worse than that of plain text, which falls short of our goal for this tool. This may need future iteration.
Copying from websites and email clients
The experience of copying from websites and email clients is mostly positive with the output mostly determined from the quality of the underlying HTML rather than any particular behaviour applied by applications.
Pages with complex layouts that involve lists can produce surprising outputs, where the conversion process attempts to embed a collection of things in a single list item.