Run results for: Copy map vs. object

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:124.0) Gecko/20100101 Firefox/124.0

Browser: Firefox 124

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Copy obj	296.4 Ops/sec
Copy map	146.0 Ops/sec

Script Preparation code:

var items = Array.from({
    length: 100000
}, (_, i) => ({
    id: `item-${i}`
}))

var dataObj = {};

items.forEach((item, i) => {
  dataObj[item.id] = {
    start: i * 30,
    end: i * 30 + 30
  }
});

var dataMap = new Map();

items.forEach((item, i) => {
  dataMap.set(item.id, {
    start: i * 30,
    end: i * 30 + 30
  });
});

Tests:

Copy obj
const obj = { ...dataObj };
Copy map
const map = new Map(dataMap);

Run results for: Copy map vs. object

Copy obj

Copy map