index.js
function expand(to, from) {

   const keys = Object.keys(from)
   for (const key of keys) {
      if (!to.hasOwnProperty(key))
         to[key] = from[key]
   }

}
function expand(to, from) {

   const keys = Object.keys(from)
   for (const key of keys) {
      if (!to.hasOwnProperty(key))
         to[key] = from[key]
   }

}
function expand ( to , from ) { const keys = Object . keys ( from ) for ( const key of keys ) { if ( ! to . hasOwnProperty ( key ) ) to [ key ] = from [ key ] } }
Add new properties on `from` to `to`.
Add new properties on from to to .