// .env
API_KEY=your_api_key <-- this won't work
REACT_APP_API_KEY=your_api_key <-- yes! this work
// Example:
// REACT_APP_GOOGLE_API_KEY=123456
node_modules
public
src
.env <---- Here
.gitignore
LICENSE
README.md
package-lock.json
package.json
// .env
REACT_APP_API_KEY=your_api_key <-- yes
API_KEY=your_api_key <-- no
// Example (from 이준형's response):
REACT_APP_WEATHER_API_KEY=123456