Run results for: structuredClone vs JSON Stringify+Parse vs manual clone

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36

Browser: Chrome 142

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 4 months ago

Test name	Executions per second
structuredClone	434204.9 Ops/sec
JSON Stringify+Parse	659703.8 Ops/sec
Manual clone	3315125.2 Ops/sec

Script Preparation code:

var object = {
    type: "FeatureCollection",
    features: [{
            type: "Feature",
            properties: {},
            geometry: {
                type: "Point",
                coordinates: [4.483605784808901, 51.907188449679325]
            }
        },
        {
            "type": "Feature",
            "properties": {},
            "geometry": {
                "type": "Polygon",
                "coordinates": [
                    [
                        [3.974369110811523, 51.907355547778565],
                        [4.173944459020191, 51.86237166892457],
                        [4.3808076710679416, 51.848867725914914],
                        [4.579822414365026, 51.874487141880024],
                        [4.534413416598767, 51.9495302480326],
                        [4.365110733567974, 51.92360787140825],
                        [4.179550508127079, 51.97336560819281],
                        [4.018096293847009, 52.00236546429852],
                        [3.9424146309028174, 51.97681895676649],
                        [3.974369110811523, 51.907355547778565]
                    ]
                ]
            }
        }
    ]
};

var copy = null;

// Manual clone

function deepCloneJsonValue(value) {
  if (value === null || typeof value !== "object") return value;

  if (Array.isArray(value)) return deepCloneJsonArray(value);
  return deepCloneJsonObject(value);
}

function deepCloneJsonObject(obj) {
  const cloned = { ...obj };
  for (const key in cloned) {
    const value = cloned[key];
    if (typeof value !== "object" || value === null) continue;
    cloned[key] = Array.isArray(value) ? deepCloneJsonArray(value) : deepCloneJsonObject(value);
  }
  return cloned;
}

function deepCloneJsonArray(arr) {
  const cloned = [];
  for (let i = 0, len = arr.length; i !== len; i++) {
    cloned.push(deepCloneJsonValue(arr[i]));
  }
  return cloned;
}

Tests:

structuredClone
copy = structuredClone(object);
JSON Stringify+Parse
copy = JSON.parse(JSON.stringify(object));
Manual clone
copy = deepCloneJsonValue(object);