Dark Knight questions

• Expected to return a value at the end of arrow function with if statement
• How to get keys and sub keys from the array of object?
• TypeError: action$.ofType(...).mergeMap is not a function
• How to establish connection for socket io and graphql?
• How to handle null values with lodash
• async function with the class in javascript
• Uncaught TypeError: Cannot read property 'injection' of undefined [closed]
• Most efficient way to pass parameters in onClick handler

Dark Knight answers