zsh function for proxy and undo proxy

proxy.zsh

function check_install {
  output="$($1 --version)"
  output_size=${#output}

  if [ $output_size -eq 0 ]; then
    echo '0'
  else
    echo '1'
  fi
}

function proxy {
  if (( $# == 0 )); then
    export http_proxy=http://127.0.0.1:8234
    export https_proxy=$http_proxy
    export all_proxy=socks5://127.0.0.1:8235
    echo "[+] HTTP Proxy on $http_proxy"
  fi
  case $1 in
    git)
      if [ $(check_install git) -ne 0 ]; then
        git config --global https.proxy $proxy
        git config --global http.proxy $proxy
        echo "[+] Git proxied on $http_proxy"
      fi
    ;;
    npm)
      if [ $(check_install npm) -ne 0 ]; then
        npm config set proxy $proxy
        npm config set https-proxy $proxy
        echo "[+] NPM proxied on $http_proxy"
      fi
    ;;
  esac
}

function unproxy {
  if (( $# == 0 )); then
    unset http_proxy
    unset https_proxy
    echo "[+] HTTP Proxy off"
  fi
  case $1 in
    git)
      if [ $(check_install git) -ne 0 ]; then
        git config --global --unset http.proxy
        git config --global --unset https.proxy
        echo "[+] Git proxy off"
      fi
    ;;
    npm)
      if [ $(check_install npm) -ne 0 ]; then
        npm config delete proxy
        npm config delete https-proxy
        echo "[+] NPM proxy off"
      fi
    ;;
  esac
}