Remove the spaces and sort

Write a function sortCharacters(text) that removes all whitespace from the string text and returns the other characters sorted.

• text has only ASCII characters: letters, digits, punctuation and whitespace.
• Whitespace is a space, a tab \t and a line break \n or \r. All of it goes, not only spaces.
• Each character is sorted by its character code, from small to large. This is the order of sort without a compare function. For example, ! and , come before the digits, the digits come before the capital letters, and the capital letters come before the small letters. So 'Z' comes before 'a'.
• Repeated characters stay: 'banana' gives 'aaabnn'.
• Return a string. An empty string or a string of only whitespace gives ''.