rule new-cap problem

[maticrivo]

Hey, i use the package hapijs/boom for server errors and all the methods are with camelCase for example new Boom.notImplemented()
standard is throwing an error

A constructor name should not start with a lowercase letter  new-cap

but i can't disable each line individually, is there a way to disable all new-cap warnings? or maybe fix the rule so it won't throw an error?

[Flet]

adding This to the top of the file should work:

/* eslint-disable new-cap */

Looking at the new-cap rule, there is an additional option called properties that can be set to false to allow this.

Right now we don't specify that option in eslint-config-standard so it falls back to the default, which is to ensure object properties are capitalized.

Does anyone have any thoughts on changing the new-cap rule to allow object properties to be lowercase?

[LinusU]

Would personally prefer to have properties: true. I don't think that is's a good (nor widespread) convention to have anything that should be newed start with a lower case letter...

[jasonkarns]

Not sure if it relates to the properties bit, but if it fixes this, I'm all for it:

new (require('foo').default)() -> (Error: "A constructor name should not start with a lowercase letter. (new-cap)")

Actually, there's the counter-example, @LinusU: it's quite common for a default export to be a constructor function. But one is clearly not able to control the capitalization of the ESM-as-CJS default export.

[LinusU]

removed spam from lordspecter13

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[feross]

@LinusU Do you have thoughts on @jasonkarns's last comment regarding it being common for a default export to be a constructor function?

[jkga]

Any update on this?

[LinusU]

Missed answering to the previous comment, so here goes: I still think that that isn't used too much, wouldn't one do something like this in those cases? 🤔

const Foobar = require('foobar').default

const blah = new Foobar()

[jkga]

@LinusU but its also being used with dynamic import

return import('./components/my-component').then(dyamicLoadedClass => { 
      return new dyamicLoadedClass.default()
      ...
})

[LinusU]

Maybe we could make an exception for .default 🤔

[dcsan]

yeah i have exact same problem on a Pusher library:

Chatkit.default({

is there a way to disable linting on just a single line and not the whole file?

[maticrivo]

You can do it by adding a comment like // eslint-disable new-cap to the end of the line

[dcsan]

hmm doesn't seem to work for me

[jkga]

@dcsan Try to put it on the very first line of the file

[dcsan]

this works at the top of the file but i just wanted to disable it for one line using the external lib call, not my own code.

/* eslint-disable new-cap */

[maticrivo]

Try with // eslint-disable-line new-cap at the end of the line or // eslint-disable-next-line new-cap one line above the code you want eslint to disable

[feross]

It's always better to always assign the name default to a name with a capitalized first letter before calling the constructor. It should always be possible to do this. For example, @jkga's code sample can be modified like this:

return import('./components/my-component').then(dyamicLoadedClass => { 
      const MyClass = dyamicLoadedClass.default
      return new MyClass()
      ...
})

Is there some reason that I'm missing why this won't work? @LinusU do you have thoughts?

We could change the rule to this:

"new-cap": ["error", { "newIsCap": true, "capIsNew": false, "properties": true, "newIsCapExceptions": ["default"] }]

which would allow the original code sample to work:

return import('./components/my-component').then(dyamicLoadedClass => { 
      return new dyamicLoadedClass.default()
      ...
})

But can someone make an argument for a situation where this is more desirable?

[LinusU]

I personally still feel that you should always reassign it to a variable with a capitalised name, but I don't feel too strongly about it...

const Foo = require('foo').default

new Foo()

import('./components/my-component').then(module => {
  const DyamicLoadedClass = module.default

  new DyamicLoadedClass()
})

import('./components/my-component').then(({ default: DyamicLoadedClass }) => {
  new DyamicLoadedClass()
})

[feross]

@LinusU Agreed. Let's not add an exception for this. If others can raise valid reasons, happy to reconsider.