New: add vue/no-unused-properties rule

[MisRob]

Hello,

we've implemented vue/no-unused-properties (disallows any unused properties, data and computed properties) as our custom internal rule recently and noticed that there's an accepted rule proposition for this logic already (#631) so we're sharing what we have.

Refs: #631

[MisRob]

Hello, recently we also added properties usage detection when a component instance accessed via a parameter in beforeRouteEnter guard to this rule.

I'm not yet sure if you're interested in this rule and also it's possible that we'll need to add more updates/fixes in the future, so instead of copying it here every time, I'm inserting a link to a location where you can always find up-to-date codes: https://github.com/learningequality/kolibri/tree/develop/packages/eslint-plugin-kolibri.

Also, we have similar rules available for component methods, mapped Vuex state, getters, mutations and actions there.

[jtwaleson]

We're using eslint-plugin-vue extensively on our code base and would love to have this implemented. Using these rules on our code base of +/- 1 year old, we found about 5% of our props to be unused.

[kazupon]

Good job!
LGTM!

[aberonni]

Friendly ping - really looking forward to using this, any idea when it will be merged?

[vperron]

Friendly ping as well !!! I'm extremely looking forward to this being merged !

[ota-meshi]

Thank you for this PR! I like your idea.
I have some requests.

[ota-meshi]

Could you change to support the destructuring assignment?

const {prop} = this

Also could you change to support the track the this?
I want to support assignment expressions as follows:

const vm = this
vm.prop

[rholic-openpath]

Can someone please make the changes requested? Would love to have this part of eslint!!

[MisRob]

Hi, I had already started working on it and then went on a long sick leave. Right now I need to catch up on other tasks I am responsible for so I think I will get to this rather after Christmas.

[maddocnc]

Also interested.
By the way, current rule also can't find unused data property if data defined like this:

data: () => ({
   neverUsed: 'but'
}),

[IWANABETHATGUY]

Can someone please make the changes requested? Would love to have this part of eslint!!

i have wrote a unofficial eslint plugin for no-unused-properties and pass the all official test, maybe you can try it.eslint-plugin-vueunused

[ibarsi]

@MisRob Would you like some support on this PR? My team is looking forward to this rule so I would be happy to help 👍🏼

[MisRob]

@ibarsi Hi thanks a lot. I believe I will eventually get to that though this year has been really busy so far. So if you can resolve @ota-meshi requests sooner than I can get back to it, you are more than welcome to do so. I briefly checked what needs to be done but don't have any codes yet.

[alb3rtuk]

Guys, our team is also very much in need of this rule. If someone could get this merged I believe a lot of ppl would be very happy :)

[IWANABETHATGUY]

Guys, our team is also very much in need of this rule. If someone could get this merged I believe a lot of ppl would be very happy :)

here is a choice, eslint-plugin-vueunused, the same effect as this pull request , pass all this pr unit test and finish the #871 (comment) feature.