useMemo on function used in .map statement

user_8455683 0
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I am pretty much new to hooks so have a question here: I have in React component function like 

const getSection = assignmentSectionId => {
    const findSection = sections.find(
      section => section.sectionRefId === assignmentSectionId,
    );

    return findSection ? findSection.name : '';
  };

and now I got suggestion to use useMemo on that function. Currently I am using like:

return (
    <List
      role="list"
      aria-label={ariaLabel}
    >
      {assignments.map(assignment => {
        const sectionName = getSection(assignment.sectionId);

        return (
          <Card
            name={sectionName}
          />
        );
      })}
    </List>
  );
};

What is the best(optimal) way to use useMemo here if it is possible?

react-hooks reactjs javascript
1 Answers

You could use the Array#map inside the useMemo .Its only re-render the list After assignments value change

const memoList = React.useMemo(()=> assignments.map(assignment => {
        const sectionName = getSection(assignment.sectionId);
        return (<Card  name={sectionName}/>)
      }),[assignments])

return (
    <List role="list" aria-label={ariaLabel}>{memoList}</List>
  );
};
user_62350470
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