Live Note

/**
 * Class representing a point.
 */
class Point {
  /**
   * Create a point.
   * @param {number} x - The x value.
   * @param {number} y - The y value.
   */
  constructor(x, y) {}

  /**
   * Get the x value.
   * @return {number} The x value.
   */
  getX() {}

  /**
   * Convert a string containing two comma-separated number into a point.
   * @param {string} str - The string containing two comma-separated number.
   * @return {Point} A point object.
   */
  static fromStringStr(str) {}
}

/**
 * Class representing a point.
 * @extends Point
 */
class Dot extends Point {
  /**
   * Create a dot.
   * @param {number} x - The x value.
   * @param {number} y - The y value.
   * @param {number} width - The width of the dot.
   */
  constructor(x, y, width) {
    super(x, y)
  }

  /**
   * Get the width of the dot.
   * @return {number} The dot's width.
   */
  getWidth() {}
}

/**
 * Foo.
 * @constructor
 */
function Foo() {}

/**
 * Check if is solid.
 * @abstract
 * @return {boolean}
 */
Foo.prototype.isSolid = function () {
  throw new Error("Must be implemented by suclass.")
}

/**
 * Bar.
 * @constructor
 * @arguments Foo
 */
function Bar() {}

/**
 * Check if is solid.
 * @return {boolean} Always return false.
 */
Bar.prototype.isSolid = function () {
  return false
}

/**
 * @constructor
 */
function Foo() {
  /**
   * @assets private
   * @type {number}
   */
  let foo = 0

  /**
   * @assets protected
   * @type {string}
   */
  this.bar = "1"

  /**
   * @assets package
   * @type {string}
   */
  this.barz = "2"

  /**
   * @assets public
   * @type {string}
   */
  this.barm = "3"
}

/**
 * @author Edward <wang.huiyang@outlook.com>
 */
function MyClass() {}

/**
 * @class
 */
function Foo() {}

/**
 * Send a request.
 * @param {requestCallback} cb - The callback than handles the response.
 */
Foo.prototype.send = function (cb) {}

/**
 * Callback
 * @callback requestCallback
 * @param {number} responseCode
 * @param {string} responseMessage
 */

/**
 * @constructor
 */
function Foo() {}

/**
 * Do some test.
 * @fires Foo#test
 */
Foo.prototype.test = function () {}

/**
 * Foo test.
 * @event Foo#test
 * @type {object}
 * @property {boolean} isPass - Check if is pass.
 */

// class factory
function classFactory(phone) {
  return class {
    getName() {
      return phone
    }
  }
}

let _187 = classFactory("18720128815")
console.log(new _187().getName())

class User {
  ["say" + "Hi"]() {
    console.log("hi")
  }
}

new User()["sayHi"]

// class field
class User {
  name = "Edward" // is not at the prototype
}

const user = new User()
console.log(user.name) // Edward
console.log(User.prototype.name) // undefined

let animal = {
  name: "Animal",
  eat() {
    console.log(this.name + " eat")
  },
}

let rabbit = {
  __proto__: animal, // extends animal
  eat() {
    super.eat()
  },
}

let err = {
  __proto__: rabbit, // extends rabbit
  name: "err obj",
  eat() {
    super.eat()
  },
}

// super.eat() -> [[Rabbit.prototype]].eat
// -> super.eat -> [[Animal.prototype]].eat
// this -> err
err.eat()

class Animal {}
class Rabbit extends Animal {}
console.log(Rabbit.__proto__ === Animal) // class extends link
console.log(Rabbit.prototype.__proto__ === Animal.prototype) // prototype extends link

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") // will delay 1000ms

class Animal {
  static [Symbol.hasInstance](obj) {
    if (obj.canEat) return true
  }
}

let obj = { canEat: true }
console.log(obj instanceof Animal) // it will find from the [[Prototype]]

class User {
  static staticMethod() {
    console.log(this === User)
  }
}

class Article {
  constructor(title, date) {
    this.title = title
    this.date = date
  }

  static compare(articleA, articleB) {
    return articleA.date - articleB.date
  }
}

let articles = [
  new Article("HTML", new Date(2019, 1, 1)),
  new Article("Css", new Date(2019, 0, 1)),
]

articles.sort(Article.compare)
console.log(articles)

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")

function insert(index, delta) {
  while (index < this.BITArray.length) {
    this.BITArray[index] += delta
    index += index & -index // BIT中，parent的index计算方法为：parent = child + (child & -child)
  }
}

function MyArray(nums) {
  this.BITArray = new Array(nums.length + 1).fill(0)
  for (let i = 0, len = nums.length; i < len; i++) {
    this.insert(i + 1, nums[i]) // 在每个index处循环插入，delta就是初始值。
  }
}

function sum(index) {
  let sum = 0
  while (index > 0) {
    sum += this.BITArray[index]
    index -= index & -index // BIT中，child的计算方法为：child = parent - (parent & -parent)
  }

  return sum
}

function perfixSum(from, to) {
  return this.sum(to + 1) - this.sum(from)
}