July 25th

@bomsy, @belen-albeza, @jbhoosreddy, @aklt, @yurydelendik, @clarkbw, @wldcordeiro, @giltayar, @jasonLaster, @julienw, @codehag,


Bug Fixes


We switched to using symbols as the basis of preview this week, which is a really big deal for a couple of reasons.

Symbols are our system for finding functions, variables, and now member expressions, object expressions, and array expressions. This is a big deal because we can now do one sweep of a file and find all of the interesting expressions a user might mouse over. Previously, we would wait for the user to hover on a token and then try to figure out what the logical expression was. This was a full AST traversal every time!

The other reason why using symbols is amazing is that we can resolve some really tricky cases. Take a look at these expressions. We can now begin supporting hovering on object keys, array items, and even object keys INSIDE OF arrays :) This will make preview much more powerful.



It’s hard to understate how much more stable breakpoints in the new debugger are. @codehag and I obsessed over 4 edge cases and found lots of stability bugs:

  1. reloading - with changed sources
  2. Source Maps - adding a breakpoiint in either source and toggling between them
  3. Sliding - adding breakpoints before functions or on lines with comments
  4. Switching between vertical and horizontal layouts

Symbol Modal

In June, we switched from showing function search results in the search bar pane to showing them in an editor style modal. Since then, there’s been a lot of polish to smooth over the rough edges. @wldcordeiro has a really nice animation in the works too!

We started working on editor style Project Search in SF and @bomsy has been making really good progress here.

We can now open project search with cmd+shift+f, search across all sources, and display the results. There’s still some polish needed here before we turn it on in nightly.