Radix sort in javascript

radixSort.js

function arrayConcatenating(...arrs) { 
    let newArr = [];

    for (let i = 0; i < arrs.length; i++) {
        newArr = newArr.concat(arrs[i]);
    }

    return newArr;
}

function arrayElementToString(elem) {
    return elem + '';
}

function radixSort(arr, pos) {
    let $0 = [];
    let $1 = [];
    let $2 = [];
    let $3 = [];
    let $4 = [];
    let $5 = [];
    let $6 = [];
    let $7 = [];
    let $8 = [];
    let $9 = [];

    for (let i = 0; i < arr.length; i++) {
        switch (arrayElementToString(arr[i])[pos]) {
            case '0':
                $0.push(arr[i])
                break;
            case '1':
                $1.push(arr[i])
                break;
            case '2':
                $2.push(arr[i])
                break;
            case '3':
                $3.push(arr[i])
                break;
            case '4':
                $4.push(arr[i])
                break;
            case '5':
                $5.push(arr[i])
                break;
            case '6':
                $6.push(arr[i])
                break;
            case '7':
                $7.push(arr[i])
                break;
            case '8':
                $8.push(arr[i])
                break;
            case '9':
                $9.push(arr[i])
                break;
        }
    }

    if (pos == 0)
        return arrayConcatenating($0,$1,$2,$3,$4,$5,$6,$7,$8,$9);

    return radixSort(arrayConcatenating($0,$1,$2,$3,$4,$5,$6,$7,$8,$9), pos - 1);
}