// interface通过extends实现继承interfaceuserName{name:string;}interfaceuserextendsuserName{age:number}letstu:user={name:'wang',age:10}// interface的extends扩展可以通过type交叉(&)类型实现type userName={name:string;}type user=userName&{age:number}letstu:user={name:'wang',age:18}// interface扩展ty...
Type又叫类型别名(type alias),作用是给一个类型起一个新名字,不仅支持interface定义的对象结构,还支持基本类型、联合类型、交叉类型、元组等任何你需要手写的类型。 type Num = number;//基本类型type StringOrNum = string | number;//联合类型type Person = {name: string};//对象类型type User = person &...
在interface extends class的上下文中,显然是取 class 是「类型」的语义。一个 interface extends 另外一个 class,可以理解为 interface 抛弃这个 class 的所有实现代码,只是跟这个 class 的「类型 shape」 进行组合。还是上面的示例代码中,从类型 shape 的角度,SomeClass 就等同于下面的 interface: 示例1-4 interfac...
interfaceAdmin{name:string;privileges:string[];}interfaceEmployee{name:string;startDate:Date;}type UnknownEmployee=Employee|Admin;functionprintEmployeeInformation(emp:UnknownEmployee){console.log("Name: "+emp.name);if("privileges"inemp){console.log("Privileges: "+emp.privileges);}if("startDate"inemp...
An interface can extend multiple interfaces: extending-multiple-interfaces.ts interfaceComponent{w:number;h:number;}interfaceClickable{onClick():void;}interfaceButtonextendsComponent,Clickable{label:string;}letbtn:Button={w:100,h:20,label:"test",onClick:function(){console.log("button clicked");}};...
Learn about interface in TypeScript. TypeScript interface is defined with 'interface' keyword and can include one or more methods or property declarations.
interface A { a: string; } interface B { b: string; } type MyType = A | B; function isA(x: MyType): x is A { return "a" in x; } function someFn(x: MyType) { if (isA(x) === true) { console.log(x.a); // works! } } We’d like to thank Mateusz Burzyński fo...
interface SomeType { /** This is an index signature. */ [propName: string]: any; } function doStuff(value: SomeType) { let x = value["someProperty"]; } This ended up being cumbersome in situations where we need to work with objects that have arbitrary properties. For example, imagine...
TypeScript编译器已经禁止了许多此类操作。然而,有些操作还是有可能绕过编译器的,例如,使用as any转换对象的类型,或者在编译TS代码时关闭严格类型检查的配置,或者在代码中通过@ts-ignore忽略类型检查。 在ArkTS中,严格类型检查不是可配置项。ArkTS强制进行部分严格类型检查,并通过规范禁止使用any类型,禁止在代码中使用...
functionextend<T,U>(first:T,second:U):T&U{constresult=<T&U>{};for(letpropinfirst){(<T>result)[prop]=first[prop];}for(letpropinsecond){if(!result.hasOwnProperty(prop)){(<U>result)[prop]=second[prop];}}returnresult;}letobj=extend({a:1},{b:2}); ...