TypeError: undefined is not a function

[trevordmiller]

Your package is great! I'm just running into one issue: when I run my npm run dev script, which uses npm-run-all I get a TypeError: undefined is not a function error, which is preventing my lint:watch script from running. I have done some debugging, and everything works as expected running npm run lint:watch by itself, or npm run dev without the lint:watch command...but I don't know how to debug it. Is this a known issue with eslint-watch in the way that it handles npm script arguments or something?

Related issue

I don't know if this is an issue with eslint-watch or npm-run-all, so I have posted the issue in both places. I do know that all of my other packages work as expected so something seems to be wrong with either eslint-watch or npm-run-all.

mysticatea/npm-run-all#9

Steps to reproduce:

• Clone the project: https://github.com/trevordmiller/npm-run-all-example
• npm install
• npm run lint:watch runs as expected
• npm run dev runs npm-run-all which works for everything except for lint:watch which is outputting TypeError: undefined is not a function

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p.s. I don't understand why eslint-watch hasn't been merged into the core eslint package?

[rizowski]

@trevordmiller Thanks for posting this, I will take a look at it a little later tonight.
As for your P.S. take a look here: eslint/eslint#2513

[rizowski]

@trevordmiller Just a bit of digging I found the culprit. As for why it is throwing, it would seem that having npm-run-all run eslint-watch -w messes with process.stdin in some way. Maybe because the process is nested within npm-run-all, i'm not a 100% sure. But to resolve this I need a little more information, what version of node are you using?

The only thing this will affect is being able to hit enter to rerun the lint. The watch should still work.

[rizowski]

@mysticatea This may still be a bug on your side since it seems when npm-run-all is running esw -w it disables the ability to hit enter and rerun the lint. Look to the above comment for a little context. I'll keep looking into this and see if there is anything I can do. Let me know if you need anything for your side.

[trevordmiller]

@rizowski Thanks for looking into it. Yeah, I'm not sure. Basically, I just want to be able to watch my linting (eslint), tests (mocha), and build (babel) at the same time using npm scripts; the -w watch command of the mocha and babel CLIs both work with the packages I have tried for running multiple commands at once (npm-run-all and parallel-shell) but I'm not sure why eslint doesn't. I'll keep tinkering. Thanks again!

[mysticatea]

@rizowski Thank you for investing. I have gotten the cause, thanks to your hint. When npm-run-all spawns child processes, it's setting ignore to stdin. I changed it to inherit, then this error disappeared.

@rizowski @trevordmiller I will release fixed version today.
I apologize for wasting your time.

[trevordmiller]

@mysticatea You didn't waste my time - that is great news! Thank you so much :) Thank you @rizowski for your help as well. You both are awesome 👍

[rizowski]

Awesome. Glad I could help. 😃