I have two arrays of objects namely arr1 and arr2 assuming the length of both are equal. Both have {id: 'some random id', ...} inner structure. I want to iterate through each object in arr1 and add a parameter checked=false if id of that object didn't belong to arr2 else add a checked=true.
Here is my present code:
for (const i of arr1) {
i.checked = false;
for (const j of arr2) {
if (i.id === j.id) {
i.checked = true;
}
}
}
How do I optimize it? Any suggestions lesser than O(n^2) is appreciated.
You can create a Set, they have O(1) access making your loop O(n)
const idSet = new Set(arr2.map(i => i.id))
for (const i of arr1) {
i.checked = idSet.has(i.id);
}
You can use Set to prepare IDs from the second array, and then use Set.prototype.has which has O(1) operation.
const arr1 = [{id: 1}, {id: 2}, {id: 3}, {id: 4}]
const arr2 = [{id: 2}, {id: 5}, {id: 4}, {id: 6}]
const ids = new Set(arr2.map(({ id }) => id))
for (const item of arr1) {
item.checked = ids.has(item.id)
}
console.log(arr1)
/* Result
[
{ id: 1, checked: false },
{ id: 2, checked: true },
{ id: 3, checked: false },
{ id: 4, checked: true }
]
*/
Quick benchmark:
Running "Array check (1000 elements)" suite...
Progress: 100%
Set.has:
15 671 ops/s, ±0.38% | fastest
two loops:
543 ops/s, ±0.48% | slowest, 96.54% slower
Finished 2 cases!
Fastest: Set.has
Slowest: two loops