Run results for: Delete or not delete

Test name	Executions per second
✓ Use filter and reduce	93,245 Ops/sec
Use undefined	66,106 Ops/sec
Use delete	61,535 Ops/sec

Use delete

const content = '0'.repeat(53000); // ~53kb
var cache = {};

let i = 100; // will give us ~5Mb
while (i--) {
    const name = `item-${i}`;
    cache[name] = content;
}

// we will delete all 100 items
function invalidateItem() {
    return true;
}

const invalidatedCache = (cache) => {
    const updatedCache = {};
    Object.assign(updatedCache, cache);
    Object.keys(cache).filter(invalidateItem).forEach((name) => delete updatedCache[name]);
    return updatedCache;
  };


invalidatedCache(cache);

Use undefined

const content = '0'.repeat(53000); // ~53kb
var cache = {};

let i = 100; // will give us ~5Mb
while (i--) {
    const name = `item-${i}`;
    cache[name] = content;
}

// we will delete all 100 items
function invalidateItem() {
    return true;
}
const invalidatedCache = (cache) => {
    const updatedCache = {};
    Object.assign(updatedCache, cache);
    Object.keys(cache).filter(invalidateItem).forEach((name) => {
        updatedCache[name] = undefined;
    });
    return updatedCache;
  };


invalidatedCache(cache);

Use filter and reduce

const content = '0'.repeat(53000); // ~53kb
var cache = {};

let i = 100; // will give us ~5Mb
while (i--) {
    const name = `item-${i}`;
    cache[name] = content;
}

// we will delete all 100 items
function invalidateItem() {
    return true;
}
const invalidatedCache = (cache) => {
    const updatedCache = Object.keys(cache).filter(invalidateItem).reduce((cacheClone, key) => {
        cacheClone[key] = cache[key];
        return cacheClone;
    }, Object.create(null));
    return updatedCache;
  };


invalidatedCache(cache);

Run results for: Delete or not delete

Delete speed can be frustrating on V8 engine, but is it so in our case?

Use delete

Use undefined

Use filter and reduce