ljharbnpmignore 
Command line tool for creating or updating a .npmignore file based on .gitignore.
Usage
Say .gitignore has:
node_modules/
build/
… so that build output is not committed, and you want .npmignore to have:
node_modules/
src/
test/
… so that source files and test files are not published, but build output is.
Automatic usage
On the command line, run npm install --save-dev npmignore.
In your .gitignore, add .npmignore so that the .npmignore file is no longer committed to version control.
In your package.json, add the following JSON to “scripts” and “publishConfig”:
"scripts": {
…
"prepack": "npmignore --auto"
…
},
"publishConfig": {
…
"ignore": [
"!build/",
"src/",
"test/"
]
…
}
Whenever you run npm pack or npm publish, an .npmignore file will automatically be created:
node_modules/
build/
# npmignore
!build/
src/
test/
Manual usage
On the command line run:
npx npmignore -i src/,test/,!build/
An .npmignore file will be created, or updated:
node_modules/
build/
# npmignore
!build/
src/
test/
Heads up!
The # npmignore comment is used to ensure that .npmignore reflects the latest changes in your .gitignore file, just by running npmignore in the command line.
_If you want to preserve everything in your .npmignore file, regardless of what is in .gitignore, just add the # npmignore comment at the top of the .npmignore file.
Verification
Run npm pack --dry-run (or npm publish --dry-run) in a modern version of npm to get a printout of the files that will be included in your npm package.
CLI commands
--auto: automatic mode. The--ignore,--unignore,keepdest, and--npmignoreoptions are incompatible with this mode.-i|--ignore: comma-separated list of patterns to add to.npmignore-u|--unignore: comma-separated list of patterns to remove from.npmignore. This will not un-ignore patterns in.gitignore.-d|--dest: optionally define a different destination filepath. Good for test driving to see what will be generated in advance.-g|--gitignore: alternate source filepath for.gitignore.-n|--npmignore: alternate source filepath for.npmignore.-k|--keepdest: avoids altering the destination file--commentLines: a comma-separated list of lines of comment text.
API
To use via API, first:
npm install --save npmignore
Then:
var npmignore = require('npmignore');
npmignore(npm, git, options);
Params
npm{String|Array}: String from.npmignoreor an array of patterns to use.git{String|Array}: String from.gitignoreor an array of patterns to use.options{Object}commentLinesArray of comment lines. Defaults to:[ 'content above this line is automatically generated and modifications may be omitted', 'see npmjs.com/npmignore for more details.' ]ignoreArray of patterns to add to the existing patterns from.gitignoreunignoreArray of patterns to remove from.npmignore. This will not un-ignore patterns in.gitignorekeepdestiftrue, avoids altering the destination file
Tests
Simply clone the repo, npm install, and run npm test
Contributing
Pull requests and stars are always welcome. For bugs and feature requests, please create an issue