Senior JS (c)

Inherited property

• Method call: this refers to the parent of this subclass

Inherited methods

• Method: save the object instance of the parent class to the prototype object subclass

• Instance of an object class is assigned to the parent subclass prototype object, and then back to the constructor means

• 一般情况下，对象的方法都在构造函数的原型对象中设置，通过构造函数无法继承父类方法。核心原理：
  
  ①将子类所共享的方法提取出来，让子类的prototype 原型对象= new 父类()  
  
  ②本质：子类原型对象等于是实例化父类，因为父类实例化之后另外开辟空间，就不会影响原来父类原型对象
  
  ③将子类的constructor指回子类的构造函数

  function Father() {
  }
  Father.prototype.sing = function () {
    console.log('唱');
  };
  function Son() {
  }
  // 这个赋值的是地址，公用一个空间，改一个就全改
  // Son.prototype = Father.prototype;
  
  // 父类的实例对象赋值给子类的原型对象,然后指回构造函数
  // 单独new一个空间给Son用{
  Son.prototype = new Father();
  Son.prototype.constructor = Son;
  Son.prototype.dance = function () {
    console.log('tiao');
  };
  var obj = new Son();
  obj.sing();
  obj.dance();
  console.log(Son.prototype);
  console.log(Father.prototype);

  • Property inheritance, method inheritance

    • Properties: call: this refers to the parent of this subclass

    • Method: instance of an object class is assigned to the parent subclass prototype object,

    • constructor prototype object of a subclass constructor must refer back to the subclass

      实现继承后，让Son指回原构造函数
      
      Son.prototype = new Father();
      
      Son.prototype.constructor = Son;

• Constructor implemented using attribute inheritance, implementation with the prototype object inheritance

The nature of the class

• class nature or function

ES5 new method

Iterate

• forEach (function (element, index, [itself iterated array]) {})
• filter () can make screening
  • array.filter(function(){})
  • Mainly used for screening
  • Returns a new array
• some()
  • Find, find the need to find value exists
    
  • Returns a Boolean value
  • return element === 100；
  • Found stop traversal
• Traverse the object
  • obj【key】