Generator: return inside a generator function

return in a generator function is special

the returned value is an IteratorResult (just like any value returned via yield)

• returns an IteratorResult (an object with the properties value and done)
• the property value is the returned value
• the property done is true
• NOTE: yield does not return done=true but done=false!
• a missing return returns {value: undefined, done: true}

mixing return and yield

• is possible
• the mix behaves different to two yields
• two yields returning values
• return a yielded value by "chaining" return and yield

Links

spec docs Description of the IteratorResult interface.
docs mdn Describes how a return statement behaves inside a generator.