面向对象3

一、原型共享

function inherit(target, origin){
  function F(){};
  F.prototype = origin.prototype;
  target.prototype = new F();
  target.prototype.constructor = target;  //target的直接构造器是谁
  target.prototype.super = origin.prototype;
}

var inherit = (function(){
  var F = function(){};
  return function(target, origin){
    F.prototype = origin.prototype;
    target.prototype = new F();
    target.prototype.constructor = target;  //target的直接构造器是谁
    target.prototype.super = origin.prototype;
  }
})();

Zhang.prototype.lastName = "zhangsan";
function Zhang(){}
function Li(){}

//Li.prototype = Zhang.prototype;

inherit(Li, Zhang);

var lisi = new Li();
var zhangsan = new Zhang();

Li.prototype.age = "20";

二、闭包

function test(){
  var num = 1;
  function demo(){
    console.log(num);
    var a = 2;
    return function(){
      console.log(a);
    }
  }
  return demo;
}

var b = test();
b();

function test(){
  var arr = [];
  for(var i = 0; i < 10; i++){
    (function(i){
      arr[i] = function(){
        console.log(i);
      }
    }(i));
  }
  return arr;
}
var returnArr = test();
for(var j = 0; j < returnArr.length; j++){
  returnArr[j]();
}

var li = document.getElementsByTagName("li");
for(var i = 0; i < li.length; i++){
  li[i].onclick = function(){
    console.log(i);
  }
}

三、命名空间

var name = "123";
var init = (function(){
  var name = "zhangsan";
  function callname(){
    f();
    console.log(name);
  };
  function f(){}
  return function(){
    callname();
  }
}());

var initLi = (function(){
  var name = "lisi";
  function callname(){
    f();
    console.log(name);
  };
  function f(){}
  return function(){
    callname();
  }
}());

四、链式调用

var zhangsan = {
  smoke:function(){
    console.log("smoking");
    return this;
  },
  drink:function(){
    console.log("drinking");
    return this;
  }
}
zhangsan.smoke().drink();

五、访问属性的两种方法

var obj = {
  name : "zhangsan"
}
console.log(obj.name)
console.log(obj["name"]);

var Zhangsan = {
  girlFriend1:"xiaozhang",
  girlFriend2: "xiaowang",
  girlFriend3: "xiaomeng",
  sayGirlFriend : function(num){
    console.log(this["girlFriend"+num]);
  }
}

六、对象枚举-各种方法

var arr = [1, 2, 3, 4, 5, 6, 7 ,8];
for(var i = 0; i < arr.length; i++){
  console.log(arr[i]);
}

var obj = {
  name : 123,
  age : 100,
  height : 180,
  weight : 200,
  __proto__ : {
    lastName : "abc"
  }
}
for(var key in obj){
  console.log(key + " " + typeof(key));
  console.log(obj.key);
  if(obj.hasOwnProperty(key)){  //去除原型链上的属性
    console.log(obj[key]);
  }
}

//A instanceof B 构造出来的
//A 对象的原型链上没有B的原型
function Person(){

}
var person = new Person();

for(var prop in window){
  console.log(prop);
  console.log(window[prop]);
}

var div = document.getElementById("box");
for(var key in div){
  console.log(key + " : " + div[key]);
}