Mootools 1.4.0, HTML, CSS, JavaScript
No-Library (pure JS), HTML, CSS, JavaScript
Using a nested loop will end up as Quadratic time complexity O(n^2)
Using a single loop and caching seen values in an object literal will end up as Linear time complexity O(n)
No-Library (pure JS), HTML, CSS, JavaScript 1.7
No-Library (pure JS), HTML, CSS, Babel + JSX