배열의 고차함수 정리 예시추가 예정

        //배열 forEach문 구조

        //리턴없음

        const numbers=[1,2,3,4]

        let pows = [];

        numbers.forEach(function(item,index){return pows[index]=item**2})

        // 같은 효과 numbers.forEach((item,index)=>{pows[index]=item**2})

        console.log(pows) // [1, 4, 9, 16]

 

 

(method) Array<number>.forEach(callbackfn: (value: number, index: number, array: number[]) => void, thisArg?: any):

void

 

 

(method) Array<any>.map<number>(callbackfn: (value: any, index: number, array: any[]) => number, thisArg?: any):

number[]

 

(method) Array<number>.filter<S>(predicate: (value: number, index: number, array: number[]) => value is 5, thisArg?: any):

S[] (+1 overload)

 

(method) Array<number>.reduce(callbackfn: (previousValue: number, currentValue: number, currentIndex: number, array: number[]) => number):

number (+2 overloads)

 

(method) Array<number>.some (predicate: (value: number, index: number, array: number[]) => unknown, thisArg?: any):

 boolean

 

(method) Array<number>.every<5>(predicate: (value: number, index: number, array: number[]) => value is 5, thisArg?:

any): this is 5[] (+1 overload)

 

(method) Array<number>.find<S>(predicate: (this: void, value: number, index: number, obj: number[]) => value is 5, thisArg?: any): 5 (+1 overload)

 

(method) Array<number>.findIndex(predicate: (value: number, index: number, obj: number[]) => unknown, thisArg?: any): number