let worker = {
  someMethod() {
    return 1
  },

  slow(x) {
    console.log("called with " + x)
    return x * this.someMethod()
  },
}

function decorator(func) {
  const cache = new Map()

  return function (x) {
    if (cache.has(x)) {
      console.log("cache hit")
      return cache.get(x)
    }

    const result = func.call(this, x)
    cache.set(x, result)

    return result
  }
}

worker.slow = decorator(worker.slow)

console.log(worker.slow(2))
console.log(worker.slow(2))

function injection(func, ...argsBound) {
  return function (...args) {
    return func.call(this, ...argsBound, ...args)
  }
}

// usage
let user = {
  firstName: "Edward",
  say(time, phrase) {
    console.log(`[${time}]: ${this.firstName} ${phrase}`)
  },
}

user.say = injection(
  user.say,
  new Date().getHours() + ":" + new Date().getMinutes()
)

user.say("Hi")

function defer(f, ms) {
  return function () {
    setTimeout(() => f.apply(this, arguments), ms)
  }
}

function sayHello(name) {
  console.log(`Hi, ${name}`)
}

const deferSay = defer(sayHello, 2000)
deferSay("Edward")

let user = {
  name: "Edward",
  hello(name) {
    console.log(`hi ${this.name}, this is ${name}`)
  },
}

Function.prototype.defer = function (ms) {
  let f = this
  return function (...arg) {
    setTimeout(() => f.apply(this, arg), ms)
  }
}

user.hello = user.hello.defer(1000)
user.hello("Ejklfj")

navigator.serviceWorker.getRegistrations().then(function (registrations) {
  for (let registration of registrations) {
    registration.unregister().then(function () {
      console.log("Service Worker Unregistered:", registration.scope)
    })
  }
})

// fill with the template
"12".padStart(3, "000") // '012'
"12".padEnd(3, "000") // '120'

// fill with space
"12".padStart(4) // '  12'

let str = "    string    "

// str.trimLeft()
str.trimStart() // 'string    '

// str.trimRight()
str.trimEnd() // '    string'