Why SyntaxError: Invalid shorthand property initializer

But as long as they are valid identifiers (i.e. they don’t contain spaces or they aren’t reserved words) quotes around property names are optional, right?

The OP had:

let person = {
  name: name,
  material: material,
  assemble: assemble,
  duration: duration
};

Which IMO, should be fine.

Or am I missing something?