JSON Killer

5MB JSON reduction for Scratch games.

An .sb3 is a zip. Costumes and sounds take up the majority of space, but the project.json needs to track them which quickly adds up. This strips out the redundant or bulky tracking without changing behavior (hopefully). So now you'll have more space if the project.json exceeds the 5MiB limit!! Please save backups though, this is highly experimental.

This all runs in-browser, nothing is uploaded!

Method

• Drops "topLevel":false, "shadow":false, "next":null. Every scratch-vm reader is a truthy test or null safe.
• Drops empty "inputs":{} and "fields":{}. The deserializer walks both with for..in.
• Drops the trailing null id from field arrays, read behind if (fieldId).
• Drops costume md5ext when it equals assetId + "." + dataFormat, which scratch-vm rebuilds. Sound md5ext stays since it has no fallback.
• Drops bitmapResolution from svg costumes that carry the default 1. Nothing on the vector path reads it: loadVector_ ignores it, and editing the costume has updateSvg write it back as 1.
• Rounds rotation centre floats to 3dp, trimming noise like 299.50337500000004.
• Deletes orphaned blocks: residue that no top level script reaches and that is attached to nothing which survives. A block still naming a live parent is a detached script rather than residue, so it is kept and reported instead.
• Checks the delete pass by attachment, not by reachability. Reachability is what chooses the blocks to drop, so asking it afterwards whether the choice was right only ever returns its own answer.
• Reports links that disagree in both directions, where a block points at something another block owns.
• Reports dropdowns naming a costume, backdrop, sound or sprite that is gone. Red hides or duplicates code and is yours to fix, yellow runs and does nothing and can be deleted, green is covered up and can be repaired. Residue the sweep removes anyway is not reported.
• Leaves a name that parses as a number alone. Scratch falls back to using it as an index, so such a block still does something.
• Reports inputs naming a block the file does not contain. In the first slot that is a blank hole in a script and the value is gone for good; underneath a plugged in reporter it reads as nothing and the dangling id is simply dropped.
• Offers to remove a duplicated custom block definition: a copy whose own pointers aim at another script’s blocks, along with the code hanging under it.
• Keeps "parent":null. getTopLevelScript loops on while (block.parent !== null).

Support

Donate at ko-fi.com/krazvalt if you wanna support me!!