参数类型

let str: string = "字符串";
let num: number = 123;
let str_num: any = 123;
str_num = "字符串";
let sex: boolean = true;
function demo(name:string): string { 
    return "字符串";
}
class Demo { 
    name: string;
    age: number;
}
let zhangsan: Demo = new Demo();
zhangsan.age = 12;
zhangsan.name = '张三';

//方法默认值

function demo(name:string,age:number=18) {
　　console.log(name);
　　console.log(age);
}
demo('zhangsan');

//可选参数

function demo(name:string,age:number=18,sex?:string) {
console.log(name);
console.log(age);
}
demo('zhangsan');