Strip Flowtype Types from JS files

strip-flowtype.sh

#!/bin/bash

# ---------------------------
# Author: Brandon Patram
# Date: 2020-02-15
#
# Description: Strip flowtype types from js files
#
# Usage: strip-flowtype.sh [path to directory]
# Examples:
# ./strip-flowtype.sh  path/to-dir
# ./strip-flowtype.sh  path/to-dir path/to-another-dir
# ---------------------------

parallel_jobs=$(sysctl -n hw.physicalcpu)
stripper_command="npx flow-remove-types"
prettier_command="npx prettier"

function build_file_list() { (
  set -e

  local files search_dirs
  files=()
  search_dirs=("$@")

  for search_dir in "${search_dirs[@]}"; do
    files+=($(find "$search_dir" -type f -name "*.js"))
  done

  echo "${files[*]}"
); }

function strip_file() {
  local file_path new_file_path

  file_path="$1"
  new_file_path=${file_path//.js/.temp.js}

  # strip types and prettierify them.
  # the flowtype stripper replaces the "// @flow" comments with an empty comment "//".
  # prettier doesn't remove that empty comment for us, so we will remove that bit manually via sed
  if (
    eval "$stripper_command" "$file_path" |
      sed -E '/\/\/[[:space:]]*$/d' |
      eval "$prettier_command" "--stdin-filepath" "$file_path" "--write"
  ) >"$new_file_path" &&
    # overwrite original file with transformed file
    mv "$new_file_path" "$file_path"; then

    printf "%s ... \e[32m%s\e[39m\n" "$file_path" "success!"
    return 0
  else
    # attempt to clean up tmp file
    rm -f "$new_file_path"

    printf "%s ... \e[91m%s\e[39m\n" "$file_path" "failure!"
    return 1
  fi
}

function strip_files() {
  local files has_failures
  files=("$@")
  has_failures=0

  # run in batches of $parallel_jobs
  for ((i = 0; i < ${#files[@]}; i += parallel_jobs)); do
    batch=("${files[@]:i:parallel_jobs}")

    for file_path in "${batch[@]}"; do
      # run in the background to transform files in parallel
      strip_file "$file_path" &
    done

    # wait for all background'd tasks to finish. then proceed to next batch
    if ! wait; then
      has_failures=1
    fi
  done

  return $has_failures
}

function main() {
  printf "%s" "Traversing search paths... "
  js_files=($(build_file_list "$@")) || exit 1
  echo "found ${#js_files[@]} files"

  echo "Starting..."
  if strip_files "${js_files[@]}"; then
    echo "Done!"
    exit 0
  else
    echo "Partially completed!"
    exit 1
  fi
}

# do work
main "$@"

If you trust Github and this script but don't want to be bothered downloading this file to run it, you can do:

bash <(curl -s https://gist.githubusercontent.com/bpatram/76364725f389ef0f5507b6d7140ccb77/raw/strip-flowtype.sh) path/to/directory path/to/another-directory