接口中的TypeScript可选功能 [英] TypeScript Optional function in Interface

问题描述

是否可以在TypeScript中使用可选功能创建接口?

Is it possible to create an Interface in TypeScript with optional function?

interface IElement {
  name: string;
  options: any;
  type: string;
  value?: string;
  validation(any): boolean; // --> should be optional.

}

推荐答案

TypeScript当前允许在接口中进行函数声明的三种语法:

There are currently three syntaxes that TypeScript allows for function declarations in interfaces:

使用带1个参数( any 类型的参数)和 boolean 返回值的 validation 函数示例:

Using your example of a validation function taking 1 parameter (of any type) and a boolean return value:

validation: {(flag: any): boolean};

或采用新的语法:

validation(flag: any) : boolean;

或替代方法是:

validation: (flag: any) => boolean;

解决方案:

因此，使用旧语法使其成为可选内容很容易:

so to make it optional with the old syntax is easy:

validation?: {(flag: any): boolean};

具有第二种语法(最近添加-多亏了 @toothbrush )

with the second syntax (recent addition - thanks to @toothbrush)

validation?(flag: any) : boolean;

或使用第三种语法(如您所见):

or in the third syntax (as you found):

validation?: (flag: any) => boolean;

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