Benchmark: empty an array in JavaScript?

Tests:

Just instantiate new array
var size = 10000; var arr1 = []; for (var i = 0; i < size; i++){ arr1.push(i); } arr1 = [];
Set length to zero
var size = 10000; var arr2 = []; for (var i = 0; i < size; i++){ arr2.push(i); } arr2.length = 0;
Splice
var size = 10000; var arr3 = []; for (var i = 0; i < size; i++){ arr3.push(i); } arr3.splice(0, arr3.length);
Pop all values
var size = 10000; var arr4 = []; for (var i = 0; i < size; i++){ arr4.push(i); } while(arr4.length > 0){ arr4.pop(); }

Historical Performance Data aggregated from 210 community runs

Desktop Results:

Chrome 148 runs

Set length to zero

41K/s

Just instantiate new array

41K/s

Splice

37K/s

Pop all values

25K/s

Fastest: Set length to zero (1.7x faster)

View exact numbers

✓ Set length to zero: 41,218 ops/sec
• Just instantiate new array: 41,122 ops/sec
• Splice: 36,972 ops/sec
• Pop all values: 24,637 ops/sec

Firefox 42 runs

Splice

31K/s

Set length to zero

31K/s

Just instantiate new array

27K/s

Pop all values

16K/s

Fastest: Splice (2.0x faster)

View exact numbers

✓ Splice: 31,435 ops/sec
• Set length to zero: 31,245 ops/sec
• Just instantiate new array: 27,302 ops/sec
• Pop all values: 15,633 ops/sec

Mobile Results:

Chrome 13 runs

Just instantiate new array

15K/s

Set length to zero

15K/s

Splice

14K/s

Pop all values

10K/s

Fastest: Just instantiate new array (1.6x faster)

View exact numbers

✓ Just instantiate new array: 15,166 ops/sec
• Set length to zero: 15,027 ops/sec
• Splice: 13,750 ops/sec
• Pop all values: 9,548 ops/sec

Safari 7 runs

Set length to zero

40K/s

Just instantiate new array

40K/s

Splice

39K/s

Pop all values

23K/s

Fastest: Set length to zero (1.8x faster)

View exact numbers

✓ Set length to zero: 40,135 ops/sec
• Just instantiate new array: 40,085 ops/sec
• Splice: 38,903 ops/sec
• Pop all values: 22,867 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Just instantiate new array
Set length to zero
Splice
Pop all values

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 16 days ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:154.0) Gecko/20100101 Firefox/154.0

Browser/OS: Firefox 154 on Linux

View result in a separate tab

Just instantiate new array

25K/s

Set length to zero

24K/s

Splice

23K/s

Pop all values

12K/s

View exact numbers

Test name	Executions per second
✓ Just instantiate new array	24,656 Ops/sec
Set length to zero	23,997 Ops/sec
Splice	23,395 Ops/sec
Pop all values	12,434 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**What is tested?**

The provided benchmark tests four different approaches to empty an array in JavaScript:

1. Instantiating a new, empty array (`arr1 = []`).
2. Setting the length of an existing array to zero (`arr2.length = 0`).
3. Using the `splice(0, arr3.length)` method to remove all elements from an array (`arr3.splice(0, arr3.length)`).
4. Popping all values from an array using a while loop (`while(arr4.length > 0){ arr4.pop();}`).

**Options comparison**

Here's a brief overview of each approach and its pros and cons:

1. **Instantiating a new array**: This method is simple and efficient, as it involves creating a new object and assigning it to the variable `arr1`. However, it requires more memory allocation compared to other methods.
2. **Setting length to zero**: This method is also straightforward and doesn't require any additional memory allocation. However, it can be slower than instantiating a new array because it needs to update the internal length property of the array object.
3. **Splice**: Using `splice(0, arr3.length)` removes all elements from the array by updating the internal length property. This method is similar to setting the length to zero but uses a different API. It can be slower than instantiating a new array because it needs to perform additional operations on the array object.
4. **Pop all values**: Using a while loop to pop all values from an array is the most memory-intensive approach, as it involves repeatedly calling the `pop()` method and discarding the returned value.

**Library usage**

None of the provided benchmark definitions uses any external libraries or frameworks.

**Special JS feature or syntax**

There are no special JavaScript features or syntax used in these benchmark definitions. The code is written in plain JavaScript and follows standard syntax and semantics.

**Other alternatives**

If you're interested in exploring alternative approaches to emptying an array, here are a few more options:

* Using `fill()` method: `arr5.fill(0);` would clear the array by filling it with zeros.
* Using `map()` method with an identity function: `arr6.map(() => 0);` would create a new array with all elements set to zero and then discard the original array.
* Using `reduce()` method with an identity function: `arr7.reduce((a, b) => a + b, 0);` would create a new array with the sum of all elements and then discard the original array.

Keep in mind that these alternatives may have different performance characteristics compared to the original benchmark definitions.

empty an array in JavaScript? (version: 0) Benchmark.js

Based on question on http://stackoverflow.com/questions/1232040/how-do-i-empty-an-array-in-javascript

Comparing performance of: `Just instantiate new array vs Set length to zero vs Splice vs Pop all values`

Created: 9 years ago by: Registered User

Go to the latest result

Just instantiate new array

Set length to zero

Splice

Pop all values

Historical Performance Data aggregated from 210 community runs

Desktop Results:

Chrome 148 runs

Firefox 42 runs

Mobile Results:

Chrome 13 runs

Safari 7 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

empty an array in JavaScript? (version: 0) Benchmark.js

Based on question on http://stackoverflow.com/questions/1232040/how-do-i-empty-an-array-in-javascript

Comparing performance of: Just instantiate new array vs Set length to zero vs Splice vs Pop all values

Created: 9 years ago by: Registered User

Go to the latest result

Just instantiate new array

Set length to zero

Splice

Pop all values

Historical Performance Data aggregated from 210 community runs

Desktop Results:

Chrome 148 runs

Firefox 42 runs

Mobile Results:

Chrome 13 runs

Safari 7 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

Related benchmarks

Comparing performance of: `Just instantiate new array vs Set length to zero vs Splice vs Pop all values`