<script>
var arr=[5,6,8,2,1];
    for(i=0;i<=arr.length-1;i++){
        for(j=0;j<=arr.length-i-1;j++){
            if(arr[j]<arr[j+1]){
            var temp=arr[j];
            arr[j]=arr[j+1];
            arr[j+1]=temp;
                }
        }                
    }
</script>