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JavaScript

Posted by Mrwan Grada
Mrwan Grada
753 Points

what kinda function is this : const MapStateToProps = state => ()

what kinda function is this : const MapStateToProps = state => () why does it end with a PARENTHESIS instead of brace?

Vince Brown
Vince Brown
16,249 Points
Vince Brown
Vince Brown
16,249 Points

Mrwan, It is just a regular arrow function but is using the shorthand syntax for return

since mapStateToProps is suppose to return an object instead of

const MapStateToProps = state => {
  return {
     name: state.user.name
     age: state.user.age
  }
}

You can write it like this

const MapStateToProps = state => ({
   name: state.user.name
   age: state.user.age
})

1 Answer

Steven Parker
Steven Parker
231,210 Points
Steven Parker
Steven Parker
231,210 Points

As Vince's examples show, one form of function definition would have a function body in braces. Another form has a single expression which is returned.

The parentheses after the "fat arrow" make it clear that the second form is being used. This is particularly useful when the return value happens to be a literal object (as in Vince's examples). Otherwise, the braces might be misinterpreted as being part of the first form without them and cause an error.