SOURCE

// 两数之和
// [1, 4, 6, 7, 8, 2, 12] 找出和为11两个数下标
const fn = (arr, target) => {
    let map = {}
    for(let i = 0; i < arr.length; i++){
        if(map[arr[i]] !== undefined){
            return [map[arr[i]], i]
        }
        map[target - arr[i]] = i
    }
    return []
}

console.log(fn([1, 4, 6, 7, 8, 2, 12], 11))