JavaScript optimize array of objects

Question

Hi I'm creating an array

this.data = [{
  label: 'Total',
  count: details.request.length,
}, {
  label: 'In-Progress',
  count: details.request.filter((obj) =>
    obj.statusId === 0 ||
    obj.statusId === 1 ||
    obj.statusId === 3 ||
    obj.statusId === 4
      ? obj
      : null,
  ).length,
}, {
  label: 'Success',
  count: details.request.filter(({ statusId }) =>
    statusId === 6 ? statusId : null,
  ).length,
  additionalObj: details.request.filter((obj) =>
    obj.statusId === 6 ? obj : null,
  ),
}, {
  label: 'Failed',
  count: details.request.filter(({ statusId }) =>
    statusId === 2 || statusId === 5 ? statusId : null,
  ).length,
  additionalObj: details.request.filter((obj) =>
    obj.statusId === 2 || obj.statusId === 5 ? obj : null,
  ),
}];

I'm creating the array in the structured I need, but have optimize this, I'm using array filter multiple times while calculating count and also for additionalObj. I'm not sure how can I use filter once for both calculating count and additionalObj. Would be great if someone can help me on optimizing my code.

FYI, this is the details structure:

details = {
  request: []
}

Answer 1

Is there any specific reason you are using filter instead of a for loop?

The code can be written as the following, which uses only a single loop:

function partition(details: { request: { statusId: number }[] }) {
    let inProgressCount = 0;

    let successCount = 0;
    const successAdditionalObj: { statusId: number }[] = [];

    let failedCount = 0;
    const failedAdditionalObj: { statusId: number }[] = [];

    details.request.forEach((req) => {
        switch (req.statusId) {
            case 0:
            case 1:
            case 3:
            case 4:
                inProgressCount += 1;
                break;

            case 6:
                successCount += 1;
                successAdditionalObj.push(req);
                break;

            case 2:
            case 5:
                failedCount += 1;
                failedAdditionalObj.push(req);
                break;

            default:
                break;
        }
    });

    return [
        {
            label: "Total",
            count: details.request.length || 0,
        },
        {
            label: "In-Progress",
            count: inProgressCount,
        },
        {
            label: "Success",
            count: successCount,
            additionalObj: successAdditionalObj,
        },
        {
            label: "Failed",
            count: failedCount,
            additionalObj: failedAdditionalObj,
        },
    ];
}

this.data = partition(dataToBeTransformed);