泛型指的任意类型 劣势：放弃了类型检查 优势： 既有类型检查有可以传入任意类型

1-1 泛型函数

function getStr<T>(msg:T){
    console.log(msg);
}
getStr<string>("hello");
getStr<object>({name:"lisi"});

1-2 约束泛型

function echoWithArr<T>(arg:T []){
    console.log(arg);
}
echoWithArr<string>(["html"]);
echoWithArr<number>([1234]);

1-3 泛型类

class NumList<T>{
    public list:Array<T> = [];
    add(val:T){
        this.list.push(val);
    }
}
var nums = new NumList<number>();
nums.add(1);
nums.add(2);
console.log(nums);
var strs = new NumList<string>();
strs.add("html")
strs.add("css");
console.log(strs);

1-4 泛型类

A 对象类型接口

interface attrs<T,U>{
    name:T,
    age:U
}
var obj:attrs<string,number> = {name:"lisi",age:10}