唐浩专栏

export class HomeComponent implements OnInit { constructor() { enum AlertLevel { info, warn, error } var emails:Array<string> = new Array(); var level:Al...

var foo = (name?:string):string =>{  return name?name:'John';}console.log(foo());

export class HomeComponent implements OnInit { constructor() { let sum = this.testSum(1,2,this.testAdd); console.log(sum); } testAdd(a:number,b:number):number { return a+b; }...

function foo():void{ if(true){ var bar:number=0; } console.log(bar);}foo();相当于function foo():void{ var bar:number; if(true){ bar=0; } console.log(bar);}所有变量声明都移到了函数的顶部ES6引入 let、const...