SOURCE

const arr = [1,3,5,7,9,2,4,6,8];
for(let i=0;i<arr.length;i++){
    for(let j =0;j<arr.length;j++){
        var n;
        if(arr[i]<arr[j]){
            n = arr[j];
            arr[j] = arr[i];
            arr[i] = n
        }
    }
}
console.log(arr)