Applescript-Apply Character Style to Select Words in InDesign CC

Question

I'm trying to apply a character style to the first several words of a paragraph. The number of words varies, but it is essentially every word before a comma.
Here's what I have so far:
tell application "Adobe InDesign CC 2014"
  tell document 1
  tell page 2
  tell (item 1 of page items whose label is "HabitsContent")
  tell paragraph 2
  repeat with i from 1 to count of characters
  if contents of character i = "," then
  exit repeat
  end if
  end repeat
  set applied character style of characters 1 thru i to "Italic"
  end tell
  end tell
  end tell
  end tell
end tell
Viewing the log of the script, it finds the comma; however, the script ends up italicizing the entire paragraph. Any ideas?

Answer 1

For anyone else who has a similar question, here's what works:
tell application "Adobe InDesign CC 2014"
tell paragraph 2 of (item 1 of page items whose label is "HabitsContent") of page 2 of document 1
set a to paragraph 1 as list
set a to text item 1 of a
set old to AppleScript's text item delimiters
set AppleScript's text item delimiters to {","}
set font style of characters 1 thru (count of text item 1 of a) to "Italic"
set AppleScript's text item delimiters to old
end tell
end tell