Performance issue with fixOrder

[vijayst]

Using fixOrder on a list of 3000 items took 30 seconds. Knowing the nature of data (only parent-child relation), an alternative fix took only 50 ms.

Random list of 3000 items:

     const rows = [];
     let j = 0;
     for (let i = 0; i < 3000; i++) {
         if (i % 3 === 0) {
             j++;
             rows.push({
                 id: j,
                 name: `Item ${j}`,
             });
        } else {
            const parent = Math.round(Math.random() * 1000);
            rows.push({
                id: 10000 + i,
                name: `Item ${10000 + i}`,
                parent
            });
        }
     }

An alternative fixOrder which works in 50 ms (not generic):

function fixOrder2(rows) {
    const parents = rows.filter(r => !r.parent);
    const children = rows.filter(r => r.parent);
    children.forEach(child => {
        const parentIndex = parents.findIndex(p => p.id === child.parent);
        parents.splice(parentIndex + 1, 0, child);
    });
    return parents;
}

[bebraw]

Good catch. I wonder what would be a good way to handle this. Could the default algorithm be made faster? If not, then adding another function might be a nice way. I can accept a PR for either.