Benchmark: Deep copy comparison

Deep copy comparison (version: 0)

Benchmarks for StackOverflow question on deep copy techniques https://stackoverflow.com/questions/7486085/copy-array-by-value/23536726#23536726

Comparing performance of: spread ... vs slice() vs splice(0) vs concat() vs JSON.parse(JSON.stringify()) vs Custom function vs Lodash.cloneDeep() vs jQuery.extend(true)

Created: 3 years ago by: Guest

Jump to the latest result

HTML Preparation code:

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js" integrity="sha512-894YE6QWD5I59HgZOGReFYm4dnWc1Qt5NtvYSaNcOP+u1T9qYdvdihz0PPSiiqn/+/3e7Jo4EaG7TubfWGUrMQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js" integrity="sha512-WFN04846sdKMIP5LKNphMaWzU7YpMyCU245etK3g/2ARYbPK9Ub18eG+ljU96qKRCWh+quCY7yefSmlkQw1ANQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>

AخA
 
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js" integrity="sha512-894YE6QWD5I59HgZOGReFYm4dnWc1Qt5NtvYSaNcOP+u1T9qYdvdihz0PPSiiqn/+/3e7Jo4EaG7TubfWGUrMQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js" integrity="sha512-WFN04846sdKMIP5LKNphMaWzU7YpMyCU245etK3g/2ARYbPK9Ub18eG+ljU96qKRCWh+quCY7yefSmlkQw1ANQ==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>

Tests:

spread ...
const arr1 = [ true, 1, "true", [], {}, function () {} ]; // Deep copies: true, 1, "true" // Shallow copies: [], {}, function () {} const arr2 = [ ...arr1 ];
x

const arr1 = [ true, 1, "true", [], {}, function () {} ];

// Deep copies: true, 1, "true"
// Shallow copies: [], {}, function () {}
const arr2 = [ ...arr1 ];

slice()

const arr1 = [ true, 1, "true", [], {}, function () {} ];

// Deep copies: true, 1, "true"
// Shallow copies: [], {}, function () {}
const arr2 = arr1.slice();

 
const arr1 = [ true, 1, "true", [], {}, function () {} ];​// Deep copies: true, 1, "true"// Shallow copies: [], {}, function () {}const arr2 = arr1.slice();

splice(0)

const arr1 = [ true, 1, "true", [], {}, function () {} ];

// Deep copies: true, 1, "true"
// Shallow copies: [], {}, function () {}
const arr2 = arr1.splice(0);

 
const arr1 = [ true, 1, "true", [], {}, function () {} ];​// Deep copies: true, 1, "true"// Shallow copies: [], {}, function () {}const arr2 = arr1.splice(0);

concat()

const arr1 = [ true, 1, "true", [], {}, function () {} ];

// Deep copies: true, 1, "true"
// Shallow copies: [], {}, function () {}
const arr2 = arr1.concat();

 
const arr1 = [ true, 1, "true", [], {}, function () {} ];​// Deep copies: true, 1, "true"// Shallow copies: [], {}, function () {}const arr2 = arr1.concat();

JSON.parse(JSON.stringify())
const arr1 = [ true, 1, "true", [], {}, function () {} ]; // Deep copies: true, 1, "true", [], {} // Shallow copies: function () {} const arr2 = JSON.parse(JSON.stringify(arr1));
const arr1 = [ true, 1, "true", [], {}, function () {} ];

// Deep copies: true, 1, "true", [], {}
// Shallow copies: function () {}
const arr2 = JSON.parse(JSON.stringify(arr1));

Custom function

function copy(aObject) {
  // Prevent undefined objects
  // if (!aObject) return aObject;

  let bObject = Array.isArray(aObject) ? [] : {};

  let value;
  for (const key in aObject) {

    // Prevent self-references to parent object
    // if (Object.is(aObject[key], aObject)) continue;

    value = aObject[key];

    bObject[key] = (typeof value === "object") ? copy(value) : value;
  }

  return bObject;
}

const arr1 = [ true, 1, "true", [], {}, function () {} ];

// Deep copies: true, 1, "true", [], {}, function () {}
const arr2 = copy(arr1);

 
function copy(aObject) {  // Prevent undefined objects  // if (!aObject) return aObject;​  let bObject = Array.isArray(aObject) ? [] : {};​  let value;  for (const key in aObject) {​    // Prevent self-references to parent object    // if (Object.is(aObject[key], aObject)) continue;​    value = aObject[key];​    bObject[key] = (typeof value === "object") ? copy(value) : value;  }​  return bObject;}​const arr1 = [ true, 1, "true", [], {}, function () {} ];​// Deep copies: true, 1, "true", [], {}, function () {}const arr2 = copy(arr1);

Lodash.cloneDeep()
const arr1 = [ true, 1, "true", [], {}, function () {} ]; // Deep copies: true, 1, "true", [], {}, function () {} const arr2 = _.cloneDeep(arr1);
const arr1 = [ true, 1, "true", [], {}, function () {} ];

// Deep copies: true, 1, "true", [], {}, function () {}
const arr2 = _.cloneDeep(arr1);
jQuery.extend(true)
const arr1 = [ true, 1, "true", [], {}, function () {} ]; // Deep copies: true, 1, "true", [], {}, function () {} const arr2 = jQuery.extend(true, [], arr1);
const arr1 = [ true, 1, "true", [], {}, function () {} ];

// Deep copies: true, 1, "true", [], {}, function () {}
const arr2 = jQuery.extend(true, [], arr1);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Experimental features:

Memory measurements supported only in Chrome.
For precise memory measurements Chrome must be launched with --enable-precise-memory-info flag.
More information: Monitoring JavaScript Memory

Test case name	Result
spread ...
slice()
splice(0)
concat()
JSON.parse(JSON.stringify())
Custom function
Lodash.cloneDeep()
jQuery.extend(true)

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 22 hours ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36 Edg/133.0.0.0

Browser/OS: Chrome 133 on Windows

View result in a separate tab

Test name	Executions per second
spread ...	31990060.0 Ops/sec
slice()	35041720.0 Ops/sec
splice(0)	21033552.0 Ops/sec
concat()	25795440.0 Ops/sec
JSON.parse(JSON.stringify())	2745774.5 Ops/sec
Custom function	2197669.8 Ops/sec
Lodash.cloneDeep()	976146.6 Ops/sec
jQuery.extend(true)	1083708.8 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 4 months ago):

It seems like you've shared two benchmark results from a testing tool, likely JSTestdriver or similar.

From the results, it appears that:

The fastest execution times are for the slice() function with an average of 62792596 executions per second.
The concat() function is slightly slower, averaging around 52792284 executions per second.
The spread function and splice(0) have execution times in the hundreds of thousands, which seems slow compared to the others.
The JSON.parse(JSON.stringify()) function has a relatively slow average execution time of around 2489870.5 executions per second.
Custom functions are not shown as they had no executions (or very few) counted.

The two benchmark tests that show up with actual numbers for Chrome 129 on Mac OS X 10.15.7 are:

slice(): 62792596 executions/second
concat(): 52792284 executions/second

LLMs can make mistakes. Check important info.

Related benchmarks: