eslint/eslint

A fully pluggable tool for identifying and reporting on patterns in JavaScript.

Matt Matheson

@mmatheson

Are fix ranges specific to rule implementations?

Jordan Harband

@ljharb

@mmatheson a hex editor is irrelevant; this is javascript and uses javascript rules

the range is specified, like all JS strings, in "code units"

and that checkmark is 1 code unit

(JS strings are UTF-16/UCS-2)

if you're applying the fix in "not javascript" then you're almost certainly going to mess something up

Matt Matheson

@mmatheson

the range is specified, like all JS strings, in "code units"

Right, I'm just asking if there's a way to specify that in bytes - I take it the answer is no

Couldn't find this in docs anywhere, can you point me in the right direction?

Jordan Harband

@ljharb

no, because that wouldn't be useful, because all fixes are applied in JS which doesn't have bytes as a concept

which part?

tbh i'm very baffled that anyone would ever think that any string info in the JS ecosystem would be in bytes unless explicitly called out as such

the fix should be applied using javascript string mechanisms. how are you applying the fix such that it cares about bytes?

Matt Matheson

@mmatheson

In c, open a file, seek to the beginning of a range and insert the replacement

re: asking for docs, i was wondering about docs around the range spec

Jordan Harband

@ljharb

why on earth would you be using C with eslint, a node program

Matt Matheson

@mmatheson

It's pretty common to have multiple languages in one repo, nice to have a unified way of linting/formatting everything at the same time

Jordan Harband

@ljharb

it is VERY uncommon, and often a very bad idea, to use "not node" for javascript tooling

even with multiple languages in one repo

C is only going to be wise to use with C, JS with JS, etc

Matt Matheson

@mmatheson

tbh I'm surprised that the spec of a machine-readable output would make the assumption about the consumer being a node program

Jordan Harband

@ljharb

how is it machine-readable?

the range is returned by a JS api

https://eslint.org/docs/developer-guide/nodejs-api#-editinfo-type is the closest doc i could find

which says it's like ".slice", which is JS semantics

Matt Matheson

@mmatheson

Ok cool thank you

Jordan Harband

@ljharb

a rule's fixer is a javascript function. it simply isn't possible to apply it without a JS runtime

the "range" on a warning output tells you where the warning is, and where the fix might be applied - it does not tell you how to apply the fix. only invoking the function can apply the fix.

Matt Matheson

@mmatheson

I assume the range is also used by various ide plugins to do syntax highlighting, not all of which will be javascript programs?

Jordan Harband

@ljharb

oh sure. but that's not applying any fixes, that's just to annotate where the error lies

(altho the most common IDEs used in JS are indeed authored in javascript, using node)

Matt Matheson

@mmatheson

Ok, so it's not totally unreasonable to try to make sense of the json output outside of javascript (and is likely being done in many places)

Jordan Harband

@ljharb

it is if you're trying to apply the fix

it is reasonable if you're just trying to annotate the warned-upon region.

often, most of that region won't be fixable

(or rather, won't be altered when a fix is applied)

Matt Matheson

@mmatheson

Ok, thanks for the clarification.

philz

@philz

Hi! I'm fighting with performance for https://github.com/typescript-eslint/typescript-eslint. We have a large, multi project (in the tsconfig.json sense) repo. We run our typescript compiles (to find compilation errors) by using tsc -b one_subproject/tsconfig.json, running parallel tsc's per the topological sort of the dependency graph. This gives us enough parallelism that our overall tsc build is slow but not devastatingly so. (We also bump up the default heapsizes for tsc.) I'm trying to apply this same pattern for eslint (run it on one tsconfig.json at a time), and, for our bigger ones, eslint is seemingly spinning forever. Whenever I interrupt it with llnode to see where it's at, it's usually compiling typescript. For some projects it finishes, and for others it runs out of memory.

I'm looking for any context on how typescript-eslint interacts with typescript, and whether there are any caches that I can manipulate directly. i.e., I'd be perfectly happy to do a full typescript build first, if then eslint could use declarations/, perhaps? I'm slogging through it, but I'd appreciate any suggestions. (I've read https://github.com/typescript-eslint/typescript-eslint/blob/master/docs/getting-started/linting/MONOREPO.md and definitely typescript-eslint/typescript-eslint#1192 seems related, and I'm trying to work around it by doing one project at a time.)