Reverse a string

Write a JavaScript function to reverse a string.

Sample Code:

function reverseString(str) {
// Enter your logic here...
}

Examples:

Input:  'Codetisan'
Output: 'nasitedoC'
Explanation: The reverse of 'Codetisan' is 'nasitedoC'.

Input: 'apple'
Output: 'elppa'
Explanation: The reverse of 'apple' is 'elppa'.