Variable of array comprehension not defined

[AluisioASG]

let a = [], b = [for (e of a) String(e)];

results in:

  1:12  error  b is defined but never used  no-unused-vars
  1:22  error  'e' is not defined           no-undef
  1:37  error  'e' is not defined           no-undef

[jeroencranendonk-wf]

Same for generator comprehensions.

[zdychacek]

Is there any plan to implement support for array/generator comprehensions?

It would be great ;)

Thanks for reply.

[sebmck]

Not sure if it's possible because it'd require patching too much of escope
and I'm not sure if it'd be possible. Patches are welcome :)

On Tuesday, 14 April 2015, Ondřej Ždych notifications@github.com wrote:

Is there any plan to implement support for array/generator comprehensions?

It would be great ;)

Thanks for reply.

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#9 (comment).

Sebastian McKenzie

[hzoo]

I guess this won't be too different from #72?

[KylePDavis]

For what it's worth, I've used this as a hack to work around this for now:

/*global cVar*///NOTE: "fix" linter errs for comprehension vars

[callumlocke]

@KylePDavis that helps, thanks

[hzoo]

Hey everyone, does #114 fix your issues?

[KylePDavis]

Thanks, @hzoo, that does seem to fix the no-undef rule complaints but it also seems to trigger block-scoped-var complaints.

Example:

"use strict";
export default [for (i of global) String(i)];
//OR: (for (i of global) String(i));

Errors:

  2:21  error  "i" used outside of binding context  block-scoped-var
  2:41  error  "i" used outside of binding context  block-scoped-var

[hzoo]

Ah dang I probably added the variable in the wrong scope.. (most likely just need to move it up a level?) or it's not that straightforward haha.

[hzoo]

@KylePDavis yeah I'm not sure at the moment =/. I guess this is besides the point but if you are using babel (with let/const) which are already block scope then you wouldn't need the rule (block-scoped-var) anymore right? Or is there something else that it catches?

[gaearon]

f921efa works great for me, only no-unused-vars false-triggering now in my comprehensions code.

[hzoo]

@gaearon Can you give me a code snippet that is failing for you? I can add no-unused-vars to the tests now.

[gaearon]

function getFirstAtom(stores) {
  return new Map([
    for (store of stores)
      [store, undefined]
  ]);
}

getFirstAtom();

stores parameter is reported to be unused.

Thanks a lot for the effort! Your work saved me a lot of headache in the past few weeks.

[hzoo]

Ah ok I didn't visit the node.right (stores in your case). Shouldn't be too hard to fix.

Awesome! It's be fun contributing and learning all this stuff (btw react-hot-loader has been great).

[hzoo]

@gaearon See if the next commit fixes it hzoo@8e254b7.

[gaearon]

@hzoo Works great. Thanks again.

[zspecza]

Still getting this issue with the below snippet, more specifically the block-scoped-var

function entries(obj) {
  return (for (key of Object.keys(obj)) [key, obj[key]])
}

[callumlocke]

Are you sure you're on the latest version? I don't get this problem any
more.
On Tue, 14 Jul 2015 at 22:27, Declan de Wet notifications@github.com
wrote:

Still getting this issue with the below snippet

function entries(obj) {
return (for (key of Object.keys(obj)) [key, obj[key]])
}

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#9 (comment).

[zspecza]

@callumlocke yep:

[hzoo]

@declandewet can you make a seperate issue for this? The original issue was for no-undef and this is for block-scoped-var/

[zspecza]

@hzoo #148 😄