Need --delete-dir-on-start or --delete-file-when-src-file-deleted option for babel --watch flag

[landyu]

Babel Configuration (.babelrc, package.json, cli command)

{
  "presets": [
    "flow",
    ["env", {
      "targets": {
        "node": true
      }
    }]
  ],
  "retainLines": true
}

Watch Script

"watchToBuild": "babel app_flow --watch --out-dir app"

Expected Behavior

when i delete some files or directories in app_flow directory, i hope these related files or directories would be deleted at same time. But actually these related files and directories still remain in the output directory app!

Current Behavior

Your Environment

software	version(s)
Babel	6.24.1
node	5.12.0
npm	3.8.6
Operating System	MacOS

[babel-bot]

Hey @landyu! We really appreciate you taking the time to report an issue. The collaborators
on this project attempt to help as many people as possible, but we're a limited number of volunteers,
so it's possible this won't be addressed swiftly.

If you need any help, or just have general Babel or JavaScript questions, we have a vibrant Slack
community that typically always has someone willing to help. You can sign-up here
for an invite.

[landyu]

if babel add --delete-dir-on-start or --delete-file-when-src-file-deleted option for babel --watch flag, will make the workflow better.

purpose: to make the source directory has the same files and directories as the output directory.
--delete-dir-on-start : when we restart the babel script, babel delete the output directory first.
--delete-file-when-src-file-deleted: start babel build script with --watch flag, babel could delete the output files or directories which were deleted from the source directories.

[loganfsmyth]

I think my preference would be a --delete-dir-on-start that is allowed when --out-dir is used, and would ensure that the directory is empty when compilation starts.

Open to suggestions for alternate names for that option since I'm not totally in love with the verbosity of that one.

--delete-file-when-src-file-deleted seems like it doesn't need an option. If we end up implementing it, having it be the default behavior seems fine to me.

[keshcode]

i would like to work on this issue

[xtuc]

@keshcode good news 👍. You can join our Slack if you need some help.