lazily get object properties

lazy-getter.js

const lazyGetter = (getters) => Object.create(null, Object
  .keys(getters)
  .reduce((result, key) => Object.assign(result, {
    [key]: {
      get () {
        const value = getters[key].call(this)
        Object.defineProperty(this, key, { value })
        return value
      },
      configurable: true
    }
  }), {}))

const foo = lazyGetter({
  spam: () => console.log('spam') || 42,
  eggs: () => console.log('eggs') || 'baz',
})

console.log(foo.spam, foo.spam, foo.eggs, foo.eggs, foo.spam)