Ray C Lin questions

• Drag and drop multiple selected draggables and revert invalid ones using Jquery UI
• Google+ JavaScript API: How to detect user sign in status?
• Google-plus sign in: the code runs twice, user was logged out right after he logs in
• Jquery validation, put error message in an existing element instead of generating a <label> tag
• Google+ sign in, PHP one-time-code/server-side flow without "Silex/twig"
• Facebook API - What is " curl -F "?

Ray C Lin answers