Hey Guillaume, you’re totally right. In the changelog for 3.1.1, it mentions “JavaScript and Sass variable types: Make default value type “raw” (unquoted) instead of “string” (quoted).” The docs have now been updated to reflect this, so while your approach is entirely valid, another way to achieve this would be by writing <Set js=af2 type=string><Field title /></Set>
I asked Eliot about this and he mentioned that while he was hesitant to introduce any backward incompatible change with this release, he acknowledged that based on some conversations with users, using unquoted values as the default value type was more intuitive and easier to use, mainly because strings are much less commonly used in Sass than colors, URLs, and other unquoted values. That decision was compounded by the fact that Sass variables already weren’t working properly in the previous version (as evidenced by this thread) so people already weren’t able to get the most flexibility out of those variables even before the 3.1.1 update. It also kinda makes the plugin more consistent since all other L&L variables are unquoted (i.e. they’re passed exactly as they’re written) by default, which makes intuitive sense.
I hope that all makes sense and I’m sorry for the hiccup this caused in your templates! I would have wanted to communicate that better but there was a communication lapse with people out on holiday when the update was released. Always a tricky balance to maintain solid communication about a plugin that’s being provided for free, but the ultimate goal is to make sure the plugin is built in the most sensible future-proof way possible while listening to user feedback. Let me know if you have any feedback about this and I’ll be sure to pass it along to the team! Thanks for bringing this up 