Count duplicate characters

Write a function duplicateCounts(text) that finds the duplicate characters in text and says how many times each of them occurs.

• text is a string. It can be empty. It has no tabs or line breaks.
• Return a plain object: the key is a character, the value is how many times it occurs in text. Not a Map.
• Put in only the characters that occur more than once.
• Spaces are skipped. All other characters count: letters, digits, punctuation.
• Case matters: 'a' and 'A' are different characters, so 'aA' gives {}.
• If no character occurs twice, return an empty object {}.
• Key order is not checked.

The object itself can be your counter: one key per character.