Sort a string in alphabetical order by Javascript without sort function

Sort a string in alphabetical order without the sort function.

Given a string S, Sort the string in alphabetical order.
Input: 'ProgRamMiNg'
Output: 'aggiMmNoPRr'

Assume that,

String S contain alphabets within the range ['a' to 'z'], ['A' to 'Z'] and white space.