Recursive implementation of merge sort

merge-sort.js

const input1 = [-5, 20, 10, 3, 2, 0];


const merge = (data, start, min, end) => {
    const temp = [];
    let i = start, j = min + 1, x = 0;

    while (i <= min && j <= end) {
        if (data[i] > data[j]) {
            temp.push(data[j++]);
        }

        if (data[i] <= data[j]) {
            temp.push(data[i++]);
        }
    }

    while (i <= min)
        temp.push(data[i++]);
    
    while (j <= end)
        temp.push(data[j++]);
    
    for (i = start; i <= end; i++)
        data[i] = temp.splice(0, 1)[0];
};

const mergeSort = (data, start, end) => {
    if (start < end) {
        const mid = Math.floor((start + end) / 2);
        mergeSort(data, start, mid);
        mergeSort(data, mid + 1, end);
        merge(data, start, mid, end);

    }

    return data;
};
 
console.log(mergeSort(input1, 0, input1.length - 1));