TS的函数重载、类型合并、类型断言

函数重载

let list5 = [1, 2, 3, 4]function findNum(id: number): number[]function findNum(): number[]function findNum(list: number[]): number[]function findNum(ids?: number | number[]): number[] {if (typeof ids === 'number') {return list5.filter((num) => num === ids)}else if (Array.isArray(ids)) {return list5.concat(ids);}else {return list5;}}

类型合并

interface People {name: string,age: number
}interface Man {sex: number
}function getUser(data: People & Man): void {console.log(data)
}getUser({name: 'cqs',age: 27,sex: 1})

类型断言

function funs(str: number | string): void {console.log((str as string).length)
}interface A {a: string
}interface B {b: string
}function fun1(str: A | B) {console.log((<B>str).b);console.log((str as B).b);}