Join strings or array of strings

str-join.js

// Concatenates all the elements of a string array, using the specified separator between each element.

function strJoin (...args) {
  const [delimiter, ...strings] = args
  if (!delimiter || !strings.length) {
    throw new Error('Invalid number of arguments.')
  }
  if (Array.isArray(...strings)) {
    const [arr] = strings
    if (!arr.length) {
      throw new Error('Array is empty.')
    }
    return strings[0].join(delimiter)
  }
  return strings.join(delimiter)
}
var message = strJoin('. ',
  'Lorem dim sum Shangai steam buns chicken feet',
  'Lorem dim sum steamed sponge cake tofu with',
  'Lorem dim sum turnip cake leek dumplings deep',
  'Lorem dim sum Pot sticker water chestnut cake'
)

console.log(message)