Live Note

Remain optimistic

Posted on Edited on In

装饰器

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/**
 * 为dom元素添加事件
 * @param {} dom
 * @param {*} type
 * @param {*} fn
 */
function addEvent(dom, type, fn) {
  if (dom.addEventListener) {
    dom.addEventListener(type, fn, false)
  } else if (dom.attachEvent) {
    dom.attachEvent("on" + type, fn)
  } else {
    dom["on" + type] = fn
  }
}

/**
 * 装饰已有对象
 * @param {*} id
 * @param {*} fn
 */
function decorator(id, fn) {
  let obj = document.querySelector(id)
  if (typeof id.onclick === "function") {
    let oldFn = id.onclick
    id.onclick = function () {
      oldFn()
      fn()
    }
  } else {
    obj.onclick = fn
  }
}

观察者模式

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let Observer = (() => {
  let _message = {}
  return {
    regist: function (type, fn) {
      if (typeof _message[type] === "undefined") {
        _message[type] = [fn]
      } else {
        _message[type].push(fn)
      }
    },
    fire: function (type, args) {
      if (!_message[type]) {
        return
      }
      let events = {
        type,
        args: args || {},
      }
      for (let i = 0, len = _message[type].length; i < len; i++) {
        _message[type][i].call(this, events)
      }
    },
    remove: function (type, fn) {
      if (_message[type] instanceof Array) {
        for (let i = _message[type].length - 1; i >= 0; i--) {
          _message[type][i] === fn && _message[type].splice(i, 1)
        }
      }
    },
  }
})()

Observer.regist("test", function (e) {
  // register
  console.log(e.type, e.args.msg)
})
Observer.fire("test", { msg: "this is some test message" }) // send

Posted on Edited on
  • background: 背景的可爱萌妹子, 当然可以自定义背景
  • beautify: 代码格式化
  • Dracula Official: 颜色主题
  • Haskell Syntax Highlighting: Haskell 语法高亮
  • HTML Snippets: HTML 自动补全
  • HTML CSS Support
  • JavaScript (ES6) code snippets: JS 自动补全
  • Markdown PDF: 神器, 但是默认会装一个 Chromium
  • npm Intellisense: 自动导入模块
  • Path Intellisense: 自动补全文件名
  • Quokka.js: 方便 debug
  • Vetur
  • vscode-icons: vscode 文件图标
  • Vue 2 Snippets
  • yddict(npm): 查词, 非常方便, 安装:sudo npm i yddict -g, 用法: yd hello
  • http-server(npm)

Posted on Edited on In 
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class Node {
  constructor(data = -1, prev = null, next = null) {
    this.data = data
    this.prev = prev // 向前指针
    this.next = next // 向后指针
  }
}

class LinkList {
  constructor() {
    this.head = this.tail = null // 首、尾指针
    this.size = 0 // 元素个数
  }

  addHead(elem) {
    let elemNode = new Node(elem)
    if (this.size == 0) {
      this.head = this.tail = elemNode
      this.size++
    } else {
      this.head.prev = elemNode
      elemNode.next = this.head
      this.head = elemNode
      this.size++
    }
    return true
  }

  deleteHead() {
    if (this.size != 0) {
      let elem = this.head.data
      this.head.prev = null
      this.head = this.head.next
      this.size--
      return elem
    } else {
      console.log("list is empty")
      return
    }
  }

  addTail(elem) {
    let elemNode = new Node(elem)
    if (this.size == 0) {
      this.head = this.tail = elemNode
      this.size++
    } else {
      elemNode.prev = this.tail
      this.tail.next = elemNode
      this.tail = elemNode
      this.size++
    }
    return true
  }

  deleteTail() {
    if (this.size != 0) {
      let elem = this.tail.data
      this.tail.next = null
      this.tail = this.tail.prev
      this.size--
      return elem
    } else {
      console.log("list is empty")
      return
    }
  }

  display() {
    let current = this.head,
      count = this.size,
      str = ""
    while (count > 0) {
      str += current.data + " "
      current = current.next
      count--
    }
    console.log(str)
  }
}
let linklist = new LinkList()
linklist.addHead(1)
linklist.addHead(2)
linklist.addHead(3)
linklist.deleteHead()
linklist.addTail(4)
linklist.display()

结果

2 1 4

Posted on Edited on In

基本用法

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let [a, b, c] = [1, 2, 3]
let [foo, [[bar], baz]] = [1, [[2], 3]]

let [, , third] = ["foo", "bar", "baz"]
third //'baz'
let [x, , y] = [1, 2, 3]
x, y //1, 3

let [head, ...tail] = [1, 2, 3, 4]
head //1
tail //[2, 3, 4]

let [x, y, ...z] = ["a"]
x //a
y //undefined
z //[]

let [x, y, z] = new Set(["a", "b", "c"])
x //'a'
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Posted on Edited on In

简单的 Stack 实现

数组实现

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class Stack {
  constructor(size = 10) {
    this.arr = [] // 栈
    this.size = size // 最大长度
    this.top = -1 // 栈顶
  }

  push(elem) {
    if (this.top == this.size) {
      this.size *= 2
    }
    this.arr[++this.top] = elem
    return true
  }

  pop() {
    let elem = this.arr[this.top--]
    return elem
  }

  peekTop() {
    if (this.top == -1) {
      console.log("stack is empty")
      return
    }
    return this.arr[this.top]
  }

  print() {
    let str = ""
    for (let i = 0; i <= this.top; i++) {
      str += this.arr[i] + " "
    }
    console.log(str)
  }
}
var stack = new Stack()
stack.push(1)
stack.push(2)
stack.pop()
console.log(stack.peekTop())
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