js继承、深度复制

继承

//父类
function parent(name) {
  this.name = name
}
//父类原型
parent.prototype.getName = function() {
  return this.name
}

/*此处不能用箭头函数，因为词法作用域将this指向全局对象window，如果不用this则可以
parent.prototype.getName = () => {
  return this.name
}
*/

//其他父类
function other(addr) {
  this.addr = addr
}

other.prototype.getAddr = function() {
  return this.addr
}

//子类
function child(age, name, addr) {
  other.call(this, addr)
  parent.call(this, name)
  this.age = age
}

child.prototype.getAge = function() {
  return this.age
}

//若子类原型添加属性则这一步是必须的，否则会访问不到
let cprototype = child.prototype
child.prototype = Object.create(parent.prototype)//单继承推荐这样写，修改child中的属性不会影响parent的prototype

Object.assign(child.prototype, cprototype, other.prototype) //混合other的prototype
child.prototype.constructor = child   //将构造函数指向child


let c = new child(22, 'tom', 'us')

console.log(c.getAge()) //22

console.log(c.getName())//tom

console.log(c.getAddr())//us

复制

function dp(obj) {
  if (typeof obj !== 'object') return // 如果属性为空则递归结束
  let newobj = obj instanceof Array ? [] : {}
  for (let key in obj) {
    if (obj.hasOwnProperty(key)) {
      newobj[key] = typeof obj[key] === 'object' ? dp(obj[key]) : obj[key]
    }
  }
  return newobj
}