泛型(宽泛的,不确定的类型)
- 使用场景:定义一个函数或类时,无法确定要使用的具体类型(返回值、参数、属性的类型不能确定)
- 泛型使用时相当于一个参数
javascript">functiondemo<T>(arg: T): T{return arg;
}
demo<number>(10)
demo<string>('你好')
demo(true)
demo(10)
泛型结合接口
javascript">interface Param<A,B> {title: string,state: A,list: B[]
}type ListType = {name:string,age:number}
const p1: Param<boolean,ListType> = {title: '泛型和接口结合使用',state: true,list: [{name:'张三',age:18},{name:'李四',age:16},]
}
泛型继承
javascript">
function getLength<T extends { length:number }>(arg: T): number{return arg.length;
}
getLength([1,2,3,'4'])
getLength('nihao') function getLength<T extends string | any[]>(arg: T): number{return arg.length;
}
getLength([1,2,3,'4'])
function getLength<T>(arg: T[]): number{return arg.length;
}
getLength<string | number>(['张三','李四',10])
类中使用泛型
javascript">
class MyClass<T>{prop: T;constructor(prop: T){this.prop = prop;}
}
type User = {name:string,age:number}
const user1:User = {name:'张三',age:18}
const c1 = new MyClass<User>( user1 )
const c2 = new MyClass<string>('张三')