MeasureThat.net

Run results for: iterating from a filled object VS iterating from a map

Comparing the overall performance when iterating on an object VS when iterating on a map

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Run details:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36 Edg/131.0.0.0
Chrome 131
Windows
Desktop
2 months ago
Test name Executions per second
small - ITERATE on filled object 523470.5 Ops/sec
big - ITERATE on filled object 4.9 Ops/sec
small - ITERATE on map 3238170.5 Ops/sec
big - ITERATE on map 186.5 Ops/sec
Script Preparation code:
​x
 
var smallArray = Array.from(Array(100).keys());
var bigArray = Array.from(Array(1000000).keys());
​
var constructObjectByAppendingToIt = (arr) => {
  const obj = {}
  for (const index of arr) {
    obj[index] = { someProp: index };
  }
  return obj
}
​
var smallFilledObject = constructObjectByAppendingToIt(smallArray);
var bigFilledObject = constructObjectByAppendingToIt(bigArray);
​
var smallMap = new Map(smallArray.map((index) => [index, { someProp: index }]));
var bigMap = new Map(bigArray.map((index) => [index, { someProp: index }]));
Tests:

  • small - ITERATE on filled object

     
    for (const [index, value] of Object.entries(smallFilledObject)) {
      value.someProp ** 2;
    }

  • big - ITERATE on filled object

     
    for (const [index, value] of Object.entries(bigFilledObject)) {
      value.someProp ** 2;
    }

  • small - ITERATE on map

     
    for (const [index, value] of smallMap) {
      value.someProp ** 2;
    }

  • big - ITERATE on map

     
    for (const [index, value] of bigMap) {
      value.someProp ** 2;
    }