JS基础语法---（数据）简单类型和复杂类型

1.     原始数据类型: number, string, boolean, undefined, null, object

2.     基本类型(简单类型), 即值类型: number, string, boolean

3.     复杂类型(引用类型): object

4.     空类型:undefined, null

 

存储空间

值类型的值在哪一块空间中存储? 栈中存储

引用类型的值在哪一块空间中存储? 对象在堆上存储, 地址在栈上存储

 

见下图：

 

 值类型和引用类型的传递

 判断下面的值：

练习1：

       var num1 = 10;
       var num2 = num1;
       num1 = 20;
       console.log(num1);//20
       console.log(num2);//10

 

练习2：

       var num = 50;
       function f1(num) {
         num = 60;
         console.log(num);//60
       }
       f1(num); //50
       console.log(num);//50

 

 练习3：

       var num1 = 55;
       var num2 = 66;
       function f1(num, num1) {
         num = 100;
         num1 = 100;
         num2 = 100;
         console.log(num);//100
         console.log(num1);//100
         console.log(num2);//100
       }
    
       f1(num1, num2);
    
    
    
       console.log(num1);//55
       console.log(num2);//100
       console.log(num);// 报错

 

练习4：

    function Person(name, age, salary) {
      this.name = name;
      this.age = age;
      this.salary = salary;
    }
    function f1(person) {
      person.name = "ls";
      person = new Person("aa", 18, 10);
    }

    var p = new Person("zs", 18, 1000);
    console.log(p.name); //zs
    f1(p);
    console.log(p.name); //ls

 

画图理解：