get-package-manager.sh

#!/bin/bash

if [ ! -f package.json ]; then
  # Default to npm regardless of missing package file.
  echo "npm"
  exit 0
fi

NODE_VERSION=$(node --version)
NODE_VERSION="${NODE_VERSION%%\.*}"
if [ "${NODE_VERSION:1}" -lt 16 ]; then
  # Only v16 or greater supports corepack.
  echo "npm"
  exit 0
fi

HAS_PACKAGE_MANAGER=$(cat package.json | jq 'has("packageManager")')
if [ "${HAS_PACKAGE_MANAGER}" != "true" ]; then
  # Package manager is not specified for the project, so npm.
  echo "npm"
  exit
fi

PACKAGE_MANAGER=$(cat package.json | jq -r '.packageManager')
PACKAGE_MANAGER=$(echo "${PACKAGE_MANAGER}" | cut -d'@' -f1)
corepack enable ${PACKAGE_MANAGER}
echo ${PACKAGE_MANAGER}