Zigzag Array

var zigzag = [4, 23, -5, -9, -19, -89];
// should look like [23, -89, 4, -19, -9, -5];

function arrSplit(arr) {
    var negArr = [], posArr = [];

    for (var i = 0; i < arr.length; i++) {
        if(arr[i] > 0) {
            posArr.push(arr[i]);
        } else {
            negArr.push(arr[i]);
        }
    }

    posArr = posArr.sort(reversePosNum);
    negArr = negArr.sort(orderNegNum);

    merge(posArr, negArr);
}

function reversePosNum(a, b) {
    return b - a;
}
function orderNegNum(a, b) {
    return a - b;
}

function merge(arr1, arr2) {
    var zigzagArr = [];
    var longArr = [];
    var shortArr = [];

    arr1.length > arr2.length ? (longArr = arr1, shortArr = arr2) : (longArr = arr2, shortArr = arr1);

    for( var i = 0; i < longArr.length; i++) {
        if( shortArr[i] ) {
            zigzagArr.push(arr1[i], arr2[i]);
        } else {
            var lastEl = longArr.pop();
            zigzagArr.push(longArr[i], lastEl);
        }

    }
    return zigzagArr;
}

// Call arrSplit() to see the final array
arrSplit(zigzag);