### 3-digit hexcode to 6-digit hexcode

Use `Array.map()`, `split()` and `Array.join()` to join the mapped array for converting a three-digit RGB notated hexadecimal colorcode to the six-digit form.

```js
const convertHex = shortHex =>
  shortHex[0] == '#' ? ('#' + shortHex.slice(1).split('').map(x => x+x).join('')) :
    ('#' + shortHex.split('').map(x => x+x).join(''));
// convertHex('#03f') -> '#0033ff'
// convertHex('05a') -> '#0055aa'
```