Continue loop on array after it's over : <p>I have an array with length of 26, each element a letter of the alphabet. I also have an N which can be from -10 to 10. 
The N takes the letter and changes it this way.
if my letter is 'a' and N = 2 my 'a' will become 'c', if my letter is 'c' and N = -1 my 'c' will become 'b'.</p>

<p>When i have a letter like 'z' which is the last element of the array and i give N a value it returns undefined.</p>

<p>How can I make it continue to loop on the array. For example if my letter is 'y' and N = 5 then it will give me a 'd'. Hope you understood me xD.</p>
