How to auto fix common linting errors reported via syntastic?

Question

I started using syntastic plugin with vim to report lint errors in my javascript code.

I also integrated eslint with syntastic, and it shows me nice errors, warnings in case they are present as per rules written in my .eslintrc file.

Is there any way in which I can fix some common errors e.g missing semi-colon, missing space etc with a key-stroke?

Edit:

I have found that eslint has an option

  --fix Automatically fix problems

which can be used for such cases. I need to run this command to let eslint fix those issues

eslint --fix -c myconfig file.js

I want to know how that can be integrated with vim?

Answer 1

As mentioned in the comments be aware of the consequences this modification has to you work environment (know exactly which eslint rules you use to "fix" things).

To answer your question: adding the option to the eslint execution with syntactic is straight forward. Simply add this to your .vimrc:

" execute eslint with --fix flag
let g:syntastic_javascript_eslint_args = ['--fix']

But as eslint is executed on the file after vim writes its buffer to the file, vim doesn't know about the fixes eslint does. So somehow vim has to load the file again (the manual way would be to simply type :e in normal/command mode). To do that, we can use the autoread option together with checktime:

" enable autoread to reload any files from files when checktime is called and
" the file is changed
set autoread

To call checktime we can use an autocmd which gets executed every time a buffer is written to a file. But as syntactic is using its own autocmd on same event BufWritePost we have to add our autocmd after syntactic adds its own. I found that this is the case when we add our autocmd on VimEnter:

" add an autocmd after vim started to execute checktime for *.js files on write
au VimEnter *.js au BufWritePost *.js checktime

So after adding all three parts to your .vimrc vim should behave as expected (lint and autocorrect on file save :w).

Answer 2

The solution given in Jepz's answer didn't completely work for me. eslint was correctly called with the --fix option. However, maybe it's because of internals that have changed, but it seems like checktime was called before the end of eslint --fix, so the file reloading didn't work properly, triggering a file has changed, are you sure you want to write to it? on the next save.

However, by digging into issues, I've discovered a hidden hook that seems to trigger after the Syntastic checks have completed, called SyntasticCheckHook (source).

With this, you can simply call checktime after the Syntastic checks have run.

Here is my final code:

set autoread

let g:syntastic_javascript_checkers = ['eslint']

" autofix with eslint
let g:syntastic_javascript_eslint_args = ['--fix']
function! SyntasticCheckHook(errors)
  checktime
endfunction

---

Edit: I've personally switched to ALE for linting, which supports autofixing natively.