Extract each occurrence from an array of objects

Question

I have a huge list of 4k+ software products.

My goal is simple. I have a list of products. Each of those products has a software value. I would like to extract each software occurrence and covert it into an object in the format {text, id}.

The code below works as I need, but I would like to know if you have a better way to do it.

softwareProducts.reduce((acc = [], {software_id, software_name}) => {
    if (acc.find((row) => row.id === software_id) === undefined) {
        acc.push({
            text: software_name,
            id: software_id
        })
    }
    return acc;
}, []);

Answer 1

Your explanation of what the code does is a little bit unclear. The algorithm you've shown dedupes an array of objects based on ids, choosing the first occurrence of each id. It's not so much that you're choosing "each occurrence" as much as "first occurrence".

You can improve on the linear lookup (.find() loops over the whole acc every time), making the quadratic algorithm a linear one using a Set, which offers constant time lookups. This essentially removes the inner loop in exchange for a bit of extra space and a bit of allocation overhead, likely well worth it on 4k+ items (always benchmark to be sure):

const softwareProducts = [
  {software_id: 1, software_name: "foo"},
  {software_id: 2, software_name: "bar"},
  {software_id: 1, software_name: "ignore this"},
  {software_id: 3, software_name: "baz"},
  {software_id: 1, software_name: "ignore this"},
  {software_id: 3, software_name: "ignore this"},
];
const resultIds = new Set();
const result = [];

for (const {software_id: id, software_name: text} of softwareProducts) {
  if (!resultIds.has(id)) {
    resultIds.add(id);
    result.push({id, text});
  }
}

console.log(result);

.reduce feels a little overworked acting as a .map and .filter. It's usually clearer as an explicit loop as shown above.

Normally, JS uses camelCase, but I assume software_name comes from an API you don't have control over. In that case, it's acceptable to use, but use softwareName if the code is under your control.

acc = [] is unnecessary; just use acc. The default argument is a no-op.

The return value of softwareProducts.reduce needs to be assigned to something. I assume you're doing so in your actual code.

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See also Create array of unique objects by property for other approaches.