Question Mark in Variable Name

Question

In React custom hook we are returning ordernumber in the below way what does question mark after the variable receipt?.order?.id means in react

export const useTest = props => {
  ...
  return {
    orderTestNumber: receipt?.test?.id
  };
}

Answer 1

its called Optional chaining (?.)

The optional chaining operator provides a way to simplify accessing values through connected objects when it's possible that a reference or function may be undefined or null.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining