function join(date, options, separator) {
   function format(option) {
      let formatter = new Intl.DateTimeFormat('en', option);
      return formatter.format(date);
   }
   return options.map(format).join(separator);
}

let options = [{day: 'numeric'}, {month: 'short'}, {year: 'numeric'}];
let joined = join(new Date, options, '-');
console.log(joined);

{ // example 1
   let formatter = new Intl.DateTimeFormat('en');
   let example = formatter.formatToParts();
   console.log(example);
}
{ // example 2
   let formatter = new Intl.DateTimeFormat('hi');
   let example = formatter.formatToParts();
   console.log(example);
}

Better would be to map a format array to resultant strings:

function join(date, options, separator) {
   function format(option) {
      let formatter = new Intl.DateTimeFormat('en', option);
      return formatter.format(date);
   }
   return options.map(format).join(separator);
}

let options = [{day: 'numeric'}, {month: 'short'}, {year: 'numeric'}];
let joined = join(new Date, options, '-');
console.log(joined);

You can also pull out the parts of a DateTimeFormat one-by-one using DateTimeFormat#format, but note that when using this method, as of March 2020, there is a bug in the ECMAScript implementation when it comes to leading zeros on minutes and seconds (this bug is circumvented by the approach above).

let date = new Date(2010, 7, 5);
let year = new Intl.DateTimeFormat('en', { year: 'numeric' }).format(date);
let month = new Intl.DateTimeFormat('en', { month: 'short' }).format(date);
let day = new Intl.DateTimeFormat('en', { day: '2-digit' }).format(date);
console.log(`${day}-${month}-${year}`);