typescript 打字稿：instanceof 检查接口
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Typescript: instanceof check on interface
提问by Bart van den Burg
Given the following code:
鉴于以下代码：
module MyModule {
export interface IMyInterface {}
export interface IMyInterfaceA extends IMyInterface {}
export interface IMyInterfaceB extends IMyInterface {}
function(my: IMyInterface): void {
if (my instanceof IMyInterfaceA) {
// do something cool
}
}
}
I get the error "Can't find name IMyInterfaceA". What's the correct way to handle this situation?
我收到错误“找不到名称 IMyInterfaceA”。处理这种情况的正确方法是什么？
采纳答案by Matija Grcic
There is no way to runtime check an interface as type information is not translated in any way to the compiled JavaScript code.
无法运行时检查接口，因为类型信息不会以任何方式转换为已编译的 JavaScript 代码。
You can check for a specific property or a method and decide what to do.
您可以检查特定的属性或方法并决定要做什么。
module MyModule {
export interface IMyInterface {
name: string;
age: number;
}
export interface IMyInterfaceA extends IMyInterface {
isWindowsUser: boolean;
}
export interface IMyInterfaceB extends IMyInterface {
}
export function doSomething(myValue: IMyInterface){
// check for property
if (myValue.hasOwnProperty('isWindowsUser')) {
// do something cool
}
}
}
回答by Artem
TypeScript uses duck typing for interfaces, so you should just check if object contains some specific members:
TypeScript 对接口使用鸭子类型，因此您应该只检查对象是否包含某些特定成员：
if ((<IMyInterfaceA>my).someCoolMethodFromA) {
(<IMyInterfaceA>my).someCoolMethodFromA();
}
