Run results for: Object key access vs array index access

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:103.0) Gecko/20100101 Firefox/103.0

Browser: Firefox 103

Operating system: Linux

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Object key access	88742.1 Ops/sec
Array index access	82928.8 Ops/sec

Script Preparation code:

var items = Array.from(
  Array(1000),
  (item, index) => ({ key: index, value: index*10 })
);
var objContainer = new Object();
var arrContainer = new Array(items.length);

// For a tenth of the number of items...
for (let i = items.length/10; i >= 0; i--) {
  // Choose a random item
  const index = Math.floor(Math.random() * items.length);
  const item = items[index];

  // Assign the item to the object and array containers
  objContainer[item.key] = item;
  arrContainer[item.key] = item;
}

Tests:

Object key access
items.forEach((item) => objContainer[item.key]?.value)
Array index access
items.forEach((item) => arrContainer[item.key]?.value)

Run results for: Object key access vs array index access

Tests the speed of accessing an item by object key vs array index.

Object key access

Array index access