TypeScript-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。

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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

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var mynum = 1;
let isValid:boolean = true;
const PI : number = 3.141592654;

联合类型

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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

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type PrimitiveArray = Array<string|number|boolean>;
type MyNumber = numbe;
type NgScope = ng.IScope;
type Callback = () => void;

函数

1.具名函数

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function greet(name?:string):string{
 if(name){
  return "Hi," + name;
 }else{
  return "Hi!";
  }
}

2.匿名函数

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var greet:(name?:string) => :string = function(name:string):string{
if(name){
  return "Hi," + name;
 }else{
  return "Hi!";
  }
}

类

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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"