function move(arr, old_index, new_index) {  
    while (old_index < 0) {  
        old_index += arr.length;  
    }  
    while (new_index < 0) {  
        new_index += arr.length;  
    }  
    if (new_index >= arr.length) {  
        var k = new_index - arr.length;  
        while ((k--) + 1) {  
            arr.push(undefined);  
        }  
    }  
     arr.splice(new_index, 0, arr.splice(old_index, 1)[0]);    
   return arr;  
}  
  
console.log(move([10, 20, 30, 40, 50], 0, 2));  
  
console.log(move([10, 20, 30, 40, 50], -1, -2));