Counting sort in javascript

countingSort.js

function countingSort(arr, maxNumber) {

    let tempArr = new Array(maxNumber + 1).fill(0);
    let returnArr = [];

    for (let i = 0; i < arr.length; i++) {
        tempArr[arr[i]] += 1;
    }

    for (let i = 1; i < tempArr.length; i++) {
        tempArr[i] += tempArr[i - 1];
    }

    for (let i = 0; i < arr.length; i++) {
        returnArr[tempArr[arr[i]] - 1] = arr[i];
        tempArr[arr[i]] -= 1;
    }

    return returnArr;
}