typescript pivot

pivot.ts

function pivot(meltedData, pivotCols: string[], varName: string, valueName: string) {
    const groups = {};

    for (const d of meltedData) {
        const key = pivotCols.map((k) => d[k]).join('|');
        const group = groups[key];
        groups[key] = {
            ...(group ? group : fromPairs(pivotCols.map((k) => [k, d[k]]))),
            [d[varName]]: d[valueName],
        };
    }

    return Object.values(groups);
}

Faster than the previous lodash implementation