//联合类型

    1. let list: (string|number)[] = ['Xcat Liu', 25];
    2. let arrr: Array<string|number> = ['Xcat Liu', 25];

    //类

    1. class Animal { 
    2.     public age: string;//成员01,public可省略，默认是public
    3.     public constructor(message: string) { //成员02
    4.         this.age = message;
    5.     }
    6.     public greet() { //成员03
    7.         return this.age;
    8.     }
    9. }
    12. class Cat extends Animal { 
    13.     constructor(age: string) { super(age); }
    14.     greet() { 
    15.         return text || '嘿嘿嘿！'
    16.     }
    17. }
    19. const tuy = new Cat('你妹');
    20. console.log(tuy.greet());

    //泛型

    1. //最基本的泛型
    2. function base<T>(arg:T):T{
    3.   return arg;
    4. }
    6. //泛型接口约束，强制需要length属性才行
    7. interface hasLength {
    8.   length: number;
    9. }
    11. function loggingIdentity<K extends hasLength>(arg: K): K {
    12.   console.log(arg.length);  // Now we know it has a .length property, so no more error
    13.   return arg;
    14. }
    16. loggingIdentity('string');
    18. //泛型接口，支持设置具体类型
    19. interface setType<T>{
    20.   (arg:T):T;
    21. }
    23. //identity 可以随意入参，但是入什么类型，一定返回什么类型
    24. function identity<T>(arg: T): T {
    25.   return arg;
    26. }
    28. //myIdentity 强制string格式的入参，返回也是string
    29. let myIdentity: setType<string> = identity;//强制指定只能输入数字
    31. myIdentity('123')
    33. //key必须是Object.keys(obj)的成员，否则报错
    34. function getProperty<T, K extends keyof T>(obj: T, key: K) {
    35.   return obj[key];
    36. }
    38. let x = { a: 1, b: 2, c: 3, d: 4 };
    40. getProperty(x, "a"); // okay
    41. getProperty(x, "m"); //报错，因为x.m = undefined;

    //private

    1. class Animal {
    2.     private name: string;
    3.     constructor(theName: string) { this.name = theName; }
    4. }
    6. new Animal("Cat").name; // 错误: 'name' 是私有的.