调用构造函数时获取 "error TS2554: Expected 1 arguments, but got 0."

Question

出现错误

error TS2554: Expected 1 arguments, but got 0.

当调用 class 实例时。我该如何解决这个问题？

class ErrorHandler {

    constructor(private errorService: BackendErrorsService) {}
    getError() {
        console.log('error called');
    }
}

const instance = new ErrorHandler().getError();

Answer 1

Angular 自动解析组件和服务的依赖关系。但是，当您致电 class 像那样:

const instance = new ErrorHandler().getError();

然后你需要提供一个依赖项BackendErrorsService。类似的东西：

let backendErrorsService = new BackendErrorsService();
const instance = new ErrorHandler(backendErrorsService ).getError();

调用构造函数时获取 "error TS2554: Expected 1 arguments, but got 0."

Getting "error TS2554: Expected 1 arguments, but got 0." when calling a constructor

typescript

angular

angular8