Using node-sass watch option with npm run-script

This is my setup for css building

"scripts": {
  "css": "node-sass src/style.scss -o dist",
  "css:watch": "npm run css && node-sass src/style.scss -wo dist"
},
"devDependencies": {
  "node-sass": "^3.4.2"
}

The -o flag sets the directory to output the css. I have a non-watching version "css" because the watching version "css:watch" ~doesn't build as soon as it's run~, it only runs on change, so I call

npm run css 

before calling

node-sass src/style.scss -wo dist

If you only want it to run on change, and not when first run, just use

"css:watch": "node-sass src/style.scss -wo dist"

Building on the previous answers, another option is to leverage NPM's custom script arguments to remain DRY by not repeating the build script arguments in the watch script:

"scripts": {
  "build:sass": "node-sass -r --output-style compressed src/style.scss -o dist",
  "watch:sass": "npm run build:sass && npm run build:sass -- -w"
}

In the above example, the watch:sass script works as follows:

1. Run the build:sass script. This will compile your CSS.
2. Run the build:sass script again, but this time include the -w flag. This will compile your CSS when one of your SASS file changes.

Notice the -- option used at the end of the watch:sass script. This is used to pass custom arguments when executing a script. From the docs:

As of [email protected], you can use custom arguments when executing scripts. The special option -- is used by getopt to delimit the end of the options. npm will pass all the arguments after the -- directly to your script.

Btw, here's my change:

"scss": "node-sass src/style.scss dist/style.css",
"start": "parallelshell \"npm run scss && npm run scss -- -w\"

Edit: Change was asynchronous script runs, for the initial compile and then with the watch flag.