不幸的是，TypeScript中没有这样的东西(更多细节请访问:https://github.com/Microsoft/TypeScript/issues/467)

但是为了解决这个问题，你可以把你的参数改成一个接口:

export interface IErrorParams {
  message: string;
  title?: string;
  autoHideAfter?: number;
}

export interface INotificationService {
  error(params: IErrorParams);
}

//then to call it:
error({message: 'msg', autoHideAfter: 42});

不幸的是，TypeScript中没有这样的东西(更多细节请访问:https://github.com/Microsoft/TypeScript/issues/467)

但是为了解决这个问题，你可以把你的参数改成一个接口:

export interface IErrorParams {
  message: string;
  title?: string;
  autoHideAfter?: number;
}

export interface INotificationService {
  error(params: IErrorParams);
}

//then to call it:
error({message: 'msg', autoHideAfter: 42});

如文档中所述，使用undefined:

export interface INotificationService {
    error(message: string, title?: string, autoHideAfter? : number);
}

class X {
    error(message: string, title?: string, autoHideAfter?: number) {
        console.log(message, title, autoHideAfter);
    }
}

new X().error("hi there", undefined, 1000);

操场上的链接。

你可以使用可选变量by ?或者如果你有多个可选变量。,例如:

function details(name: string, country="CA", address?: string, ...hobbies: string) {
    // ...
}

在上述:

必须填写姓名 Country是必选项，有默认值 地址可选 嗜好是一个可选参数数组

你可以在接口上指定多个方法签名，然后在类方法上重载多个方法:

interface INotificationService {
    error(message: string, title?: string, autoHideAfter?: number);
    error(message: string, autoHideAfter: number);
}

class MyNotificationService implements INotificationService {
    error(message: string, title?: string, autoHideAfter?: number);
    error(message: string, autoHideAfter?: number);
    error(message: string, param1?: (string|number), param2?: number) {
        var autoHideAfter: number,
            title: string;

        // example of mapping the parameters
        if (param2 != null) {
            autoHideAfter = param2;
            title = <string> param1;
        }
        else if (param1 != null) {
            if (typeof param1 === "string") {
                title = param1;
            }
            else {
                autoHideAfter = param1;
            }
        }

        // use message, autoHideAfter, and title here
    }
}

现在所有这些都可以工作了:

var service: INotificationService = new MyNotificationService();
service.error("My message");
service.error("My message", 1000);
service.error("My message", "My title");
service.error("My message", "My title", 1000);

.．.INotificationService的error方法将有以下选项:

操场上

这与@Brocco的回答几乎相同，但略有不同:只在对象中传递可选参数。(并使params对象可选)。

它最终有点像Python的**kwargs，但又不完全是。

export interface IErrorParams {
  title?: string;
  autoHideAfter?: number;
}

export interface INotificationService {
  // make params optional so you don't have to pass in an empty object
  // in the case that you don't want any extra params
  error(message: string, params?: IErrorParams);
}

// all of these will work as expected
error('A message with some params but not others:', {autoHideAfter: 42});
error('Another message with some params but not others:', {title: 'StackOverflow'});
error('A message with all params:', {title: 'StackOverflow', autoHideAfter: 42});
error('A message with all params, in a different order:', {autoHideAfter: 42, title: 'StackOverflow'});
error('A message with no params at all:');