声明合并
如果定义了两个相同名字的函数、接口或类,那么它们会合并成一个类型。
接口的合并
接口中的属性在合并时会简单的合并到一个接口中:
interface Alarm {
price: number;
}
interface Alarm {
weight: number;
}
相当于:
interface Alarm {
price: number;
weight: number;
}
注意,合并的属性的类型必须是唯一的:
interface Alarm {
price: number;
}
interface Alarm {
price: number; // 虽然重复了,但是类型都是 `number`,所以不会报错
weight: number;
}
interface Alarm {
price: number;
}
interface Alarm {
price: string; // 类型不一致,会报错
weight: number;
}
// index.ts(5,3): error TS2403: Subsequent variable declarations must have the same type. Variable 'price' must be of type 'number', but here has type 'string'.
接口中方法的合并,与函数的合并一样:
interface Alarm {
price: number;
alert(s: string): string;
}
interface Alarm {
weight: number;
alert(s: string, n: number): string;
}
相当于:
interface Alarm {
price: number;
weight: number;
alert(s: string): string;
alert(s: string, n: number): string;
}
类的合并
类的合并与接口的合并规则一致。
标签:string,Alarm,合并,number,interface,声明,price From: https://www.cnblogs.com/wjw1014/p/17928761.html