How to decode heatshrink

[espruino-discuss2]

Posted at 2022-05-07 by Asynchronous

I compress an object: schedule = require("heatshrink").compress(JSON.parse(require("Storage").read("CustomSchedule.json")));
Printing the value of schedule returns new Uint8Array([0, 2]).buffer.
I then decompress using console.log(require("heatshrink").decompress(schedule)); and get new ArrayBuffer(2).
How can I convert the ArrayBuffer back to an object?

[gfwilliams]

Posted at 2022-05-09 by @gfwilliams

I'm afraid you can't, since heatshrink compresses only a sequence of bytes, not a structure.

If you want to compress it and get the data back, you'll need to compress the JSON, so:

schedule = require("heatshrink").compress(require("Storage").read("CustomSchedul­e.json"));

However this may be counterproductive. require("Storage").read effectively 'memory maps' the JSON that's in flash memory, so it doesn't actually use up any RAM when it's sitting there as a string.

It's only when you decode it with JSON.parse that it ends up using a bunch of memory