how to merge two sorted array in one sorted array in JavaScript without using sort()

Question

In this program merged two array and then sorted using temp.but this not correct method.because two array are sorted ,so method should be unique i.e. merging of two sorted i

Answer 1

Based on Eric Lundgren's answer above, but this fixes a couple of major bugs and is more efficient. Worked for me in production. I included using a sort function for more complex solutions - for this simple case you can just test for a > b as in Eric's answer if you want.

function mergeSortedArray(a, b) {
    var sorted = [], indexA = 0, indexB = 0;

    while (indexA < a.length && indexB < b.length) {
        if (sortFn(a[indexA], b[indexB]) > 0) {
            sorted.push(b[indexB++]);
        } else {
            sorted.push(a[indexA++]);
        }
    }

    if (indexB < b.length) {
        sorted = sorted.concat(b.slice(indexB));
    } else {
        sorted = sorted.concat(a.slice(indexA));
    }

    return sorted;
}

function sortFn(a, b) {
    return a - b;
}

console.log(mergeSortedArray([1,2,3,5,9],[4,6,7,8]));