Minification problems

Continuation of: original post

In custom.html, merge all of imageclock.draw.js into imageclock.app.js - and then it'll all get minified together and should end up faster.

I tried this and got 5-10% faster time to first complete draw by pretokenization alone. Additionally using minification got about 5% on top of that. So pretty worthwhile I think.

for (let a of a.getPoints())
It looks like a minifier bug? a = [3,4,5]; for (let a of a) console.log(a); fails in Node.js too so it's not a problem with Espruino not being spec compliant.

That could well be. I could not find similar problem descriptions, but redeclaring a variable existing in an outside scope sure seems fishy.
Edit: I have tried running the closure compiler on the same code and it creates for (var n of a.getPoints()) instead

the minifier generated a constant named g into a block of code calling Bangle.load which in turn calls g.reset()
That feels like another minifier bug?

I don't know. Does the minifier actually know that Bangle.load can call g.whatever()? This is probably a quite seldom problem, since you need to have code using enough variables that the minifier gets to "g" as a variable name. Maybe it would be enough to prohibit the minifier from using "g" as a name?

redeclaring a variable existing in an outside scope sure seems fishy.

Yes... The problem I have is esprima seems more or less unmaintained now - and it's hard to find a decent minifier that can be bundled up and run in the browser and node.js.

Someone attempted using rollup at one point. but as I remember it was huge and ended up being a bit of a mess to use.

Does the minifier actually know that Bangle.load can call g.whatever()?

Oh, I misunderstood.

That shouldn't actually be a problem. Or was it generating a new global variable of that name?

If you do:

function boom() {
  g.reset();
}

function hello() {
  var g = "blah";
  boom();
}

or:

function boom() {
  g.reset();
}

{
  let g = "blah";
  boom();
}

Then there should be no problem - the function that uses g will only do it from the global scope, not the local one

Regarding another minifier than esprima, have you tried uglifyjs? It is build for Node.js and there are projects using it wrapped for a browser like https://github.com/Skalman/UglifyJS-onli­ne. I know close to nothing about the whole NPM/Node world, it's just what I had seen used for minification sometime before.

As for the minification problem in iconlaunch, I currently can not reproduce that because of changes I have done to iconlaunch since then. Probably because the problematic code now just uses other variable names after minification. I will have an eye on that and try to build a minimum sample if I see it happening again.

I can't remember exactly... but it looks from the commit history like we never put uglifyjs in publicly - so may it's an option...

Just a note on another minifier problem:
Classes defined in the script seem to be removed by the minifier. Wrapping the script in a scope apparently works around this. At least it does for 2047pp. https://github.com/espruino/BangleApps/p­ull/2500