TypeScript-01-变量、基本类型和运算符

基本类型

基本类型有boolean、number、string、array、void。所有类型在TypeScript中，都是一个唯一的顶层的Any Type 类型的自类型。any关键字代表这种类型。

类型	声明方式
boolean	var isDone:boolean=false
number	var height = 6;
string	var name:string="bob
array	var list:number[]=[1,2,3]
enum	enum Color {Red,Green,Blue}
any	var notsure:any = 4;notsure = "maybe a string instaed"; notsure = false;

在TypeScript中，我们不能把null或undefind当作类型使用。

var testVar : null;//错误，类型错误

var testVar : undefined;//错误，找不到undefined

 var、let和const

    在TypeScript中，当声明一个变量时，可以使用var、let和const关键字

var mynum = 1;

let isValid:boolean = true;

const PI : number = 3.141592654;

联合类型

    var path :string[]|string;

path  = '/temp/log.xml';

path = ['/temp/log.xml','/temp/error.xml'];

类型别名

TypeScript允许用type关键字声明类型别名

type PrimitiveArray = Array<string|number|boolean>;

type MyNumber = numbe;

type NgScope = ng.IScope;

type Callback = () => void;

函数

1.具名函数

function greet(name?:string):string{

if(name){

return "Hi," + name;

}else{

return "Hi!";

}

}

2.匿名函数

var greet:(name?:string) => :string = function(name:string):string{

if(name){

return "Hi," + name;

}else{

return "Hi!";

}

}

类

class Character{

fullname:string;

constructor(firstname:string,lastname:string){

this.fullname = firstname + "  " + lastname;

}

greet(name?:string){

if(name){

return "Hi!" + name + "!my name is "  + this.fullnamel;

}else{

return "Hi! my name is " + this fullname ;

}

}

}

var spark = new Character("Jacob","Keyes");

var msg = spark.greet();//"Hi! my name is Jocob Keyes";

var msg1 = spark.greet("Dr. Halsey");//"Hi!Dr. Hasey! my name is Jacob Keyes"