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Javascript – TypeError: groupBy(…).map is not a function

I tried to group json data with specific key like that:

function groupBy(items) {
    return items.reduce((acc, curr) => {
      if (curr.league?.id) {
        const { id } = curr.league;
        const currentItems = acc[id];
    
        return { 
          ...acc,
          [id]: currentItems ? [...currentItems, curr] : [curr]
        };
      }
      return acc;
    }, {});
  }

    console.log(groupBy(matches))

Then I get a correct result like that

but when I tried to get data using The map() method like that :

groupBy(matches).map((match, index) => ( ..... ))

I get this error :

groupBy(...).map is not a function TypeError: groupBy(...).map is not a function

Any Idea?

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2

Answers


  1. 0

    Your groupBy function intakes an array, but returns an object. The .map function is only available for arrays. To iterate over any object you can use a forin loop, or map over the objects keys with Object.keys.

    This answer does a great job covering how to map over an object: https://stackoverflow.com/a/14810722/7638738

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  2. 0

    groupBy is returning an object and .map is native to arrays. Using Object.keys, which is the equivalent of .map to iterate over an object.

    Check this answer out on how to make use of it.

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