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JavaScript

Lars Olof Berg
Lars Olof Berg
836 Points
Posted by Lars Olof Berg
Lars Olof Berg
836 Points

Why is not the key included in the spread function?

Why do you need to add the key outside the spread function? Is there something special with a key?

      {props.planets.map( planet => 
        <Planet
          {...planet}
          key={planet.id}
        />      
      )}

1 Answer

Lauren Clark
Lauren Clark
33,155 Points
Lauren Clark
Lauren Clark
33,155 Points

It's iterating through each item in the array by the key name, we need a key named "key" yet the array only contains "id" so we're essentially making the id available through props as "key" rather than "id". If we didn't do this, if you access planet.key, nothing would happen as this doesn't exist in the array. From what I understand, and have seen the prop need to be explicitly named "key" so it wouldn't work with "id" -- React needs the key prop.