Solution in JS

solutions.js

function findSomePair(arr, sum) {
    arr = arr || [];
    sum = sum || 0;

    let outs = {},
        map = new Map();

    if (arr.length <= 1) {
        outs["pairElementIndex1"] = -1;
        outs["pairElementIndex2"] = -1;
        return outs;
    }

    for(let i = 0; i < arr.length; ++i) {
        if (map.has(arr[i])) {
            outs["pairElementIndex1"] = i;
            outs["pairElementIndex2"] = map.get(arr[i]);
            return outs;
        } else {
            map.set(sum - arr[i], i);
        }
    }
    outs["pairElementIndex1"] = -1;
    outs["pairElementIndex2"] = -1;
    return outs;
}


function testFindSomePair() {
    let arr = [1, 4, 5, -1, 4, 7, 8, 8, 9, 12],
        outs;

    outs = findSomePair(arr, 21);
    console.log(`Element Pair at ${outs.pairElementIndex1} and ${outs.pairElementIndex2}`);
}


function reverse(arr, start, end) {
    let temp;
    while (start < end) {
        temp = arr[start];
        arr[start] = arr[end];
        arr[end] = temp;
        start++;
        end--;
    }
}


function reverseEachWord(arr) {
    let startInd = 0,
        i = 0;
    while (true) {
        if (arr[i] === ' ') {
            reverse(arr, startInd, i - 1);
            startInd = i + 1;
        } else if(i === arr.length) {
            reverse(arr, startInd, i - 1);
            break;
        }
        i++;
    }
}


function testReverseEachWord() {
    let arr = "This is our country".split("");
    reverseEachWord(arr);
    console.log(arr.join(""));
}


(function () {
    testFindSomePair();
    testReverseEachWord();
})();