ES5的类和继承

function People(name, age) {
    // 实例属性
    this.name = name;
    this.age = age;
    People.count++;
}
//静态属性
People.count = 0;
// 静态方法
People.getCount = function() {
    console.log('当前共有' + People.count + '个人');
}

// 实例方法
People.prototype.showName = function() {
    console.log('名字是' + this.name)
};

let p1 = new People('kiw', 18)
p1.showName();
console.log('p1', p1); //p1 People {name: "kiw", age: 18}
let p2 = new People('zhangsan1', 20)
p2.showName();
console.log('p2', p2) // p2 People {name: "zhangsan1", age: 20}

console.log(People.count) //2
People.getCount(); // 当前共有2个人

let str = new String('kiw');
console.log(str); // String {"kiw"}  new出来的一定是对象
console.log(typeof str); //object

let arr = new Array(1, 2, 3);
console.log(arr); // [1, 2, 3]

let obj = new Object({
    name: 'kiw',
    age: '18',
});
console.log(obj); //{name: "kiw", age: "18"}