Live Note

let data = {
  tag: "div",
  children: [
    {
      tag: "span",
      children: [
        {
          tag: "#text",
          content: "hello world",
        },
      ],
    },
    {
      tag: "p",
      children: [
        {
          tag: "#text",
          content: "This is a paragraph!",
        },
        {
          tag: "h1",
          children: [
            {
              tag: "#text",
              content: "This is a H1 tag",
            },
          ],
        },
        {
          tag: "h6",
          children: [
            {
              tag: "#text",
              content: "and I'm h6",
            },
          ],
        },
      ],
    },
  ],
}

class VDOM {
  constructor(data) {
    this.tag = data.tag
    this.children = data.children
    this.content = data.content
  }
  static render(data) {
    let _this = new VDOM(data)
    if (_this.tag === "#text") {
      return document.createTextNode(_this.content)
    }
    let node = document.createElement(_this.tag)
    _this.children.map((child) => node.appendChild(VDOM.render(child)))
    return node
  }
}

let diff = (root, oldV, newV, current = 0) => {
  if (!oldV) root.appendChild(newV)
  else if (!newV) root.removeChild(root.childNodes[current])
  else if (newV.tag !== oldV.tag || newV.content !== oldV.content)
    root.replaceChild(new VDOM(newV).render(), root.childNodes[current])
  // 递归判断
  else
    for (let i = 0; i < newV.children.length || i < oldV.children.length; i++)
      diff(root.childNodes[i], oldV.children[i], newV.children[i], i)
}
document.querySelector("#root").appendChild(VDOM.render(data))

// 类式继承
// parent
function SuperClass() {
  this.superValue = true
}
SuperClass.prototype.getSuperValue = function () {
  return this.superValue
}

// child
function SubClass() {
  this.subValue = false
}
SubClass.prototype = new SuperClass()
SubClass.prototype.getSubValue = function () {
  return this.subValue
}

let child = new SubClass()
console.log(child.getSuperValue()) // true
console.log(child.getSubValue()) // false