To put in your bash_rc

__git_status_flag.bash

# git status with a dirty flag
function __git_status_flag {
  git_status="$(git status 2> /dev/null)"
  clean_pattern="working tree clean" # For macOS. For Linux: "working directory clean"
  remote_pattern="Your branch is (.*)"
  diverge_pattern="Your branch and (.*) have diverged"
  if [[ ! ${git_status} =~ ${clean_pattern} ]]; then
    state="⚡ "
  fi

  if [[ ${git_status} =~ ${remote_pattern} ]]; then
    if [[ ${BASH_REMATCH[1]} == "ahead" ]]; then
      remote="🔺️ "
    elif [[ ${BASH_REMATCH[1]} == "behind" ]]; then
      remote="🔻 "
    fi
  fi

  if [[ ${git_status} =~ ${diverge_pattern} ]]; then
    remote="⚠️ "
  fi

  echo "${state}${remote}"
}

Example use:

PS1='\[\e[32m\]\u@\[\e[1m\]\h\[\e[22m\]:\[\e[1;34m\]\w\[\e[22;35m\]$(__git_ps1 " [\[\e[33m\]$(__git_status_flag)\[\e[35m\]%s]")\[\e[33m\] \$ \[\e[0m\]'