Switch Config by arg at package.json for npm run.

config.abc.json

{
  "a" : 1,
  "b" : 2,
  "c" : 3
}

config.xyz.json

{
  "x" : 1,
  "y" : 2,
  "z" : 3
}

index.js

"use strict";

const fs = require( "fs" );

let args = [];

process.argv.forEach( ( v, idx ) => {
  if ( idx >= 2 ) {
    args.push( v );
  }
});

console.log( args );

console.log( JSON.parse( fs.readFileSync( "./config.json", "utf8" ) ) );

package.json

{
  "name": "Switch!",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "switch": "f(){ ln -s config.json{.$1,}; shift; node index.js $@; rm config.json; }; f"
  },
  "author": ""
}