Benchmark: shallow copy of array

Script Preparation code:

arr0 = [];
for(var i=0;i<10000;i++){
  arr0.push("var "+i);
}

Tests:

slice
var other = arr0.slice()
push-apply
var other = []; Array.prototype.push.apply(other, arr0);
the ...operator
var other = [...arr0];
for-push
var other = []; for(var i=0;i<arr0.length;i++){ other.push(arr0[i]); }
concat
var other = []; other = other.concat(arr0);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
push-apply
the ...operator
for-push
concat

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:93.0) Gecko/20100101 Firefox/93.0

Browser/OS: Firefox 93 on Ubuntu

View result in a separate tab

Test name	Executions per second
slice	11879.8 Ops/sec
push-apply	6931.0 Ops/sec
the ...operator	2230.7 Ops/sec
for-push	2406.2 Ops/sec
concat	3903.3 Ops/sec

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

LLMs can make mistakes. Check important info.

**What is being tested?**

MeasureThat.net is testing the performance of different ways to create a shallow copy of an array in JavaScript. The test cases are designed to measure the execution speed of various methods, including:

1. `slice()`
2. `push()` with `apply()`
3. The spread operator (`...`)
4. `for` loop and `push()`

**Options compared**

The options being compared are different approaches to creating a shallow copy of an array in JavaScript. Each test case has a unique approach, which is measured for its execution speed.

**Pros and Cons of each approach:**

1. **`slice()`**: This method creates a new array by copying elements from the original array. Pros: concise and efficient. Cons: may not work as expected if the original array is modified.
2. **`push()` with `apply()`:** This method pushes all elements from the original array onto a new array using the `apply()` method. Pros: can be used with arrays of any type, including nested arrays. Cons: less concise and may have performance overhead due to the use of `apply()`.
3. **The spread operator (`...`):** This method creates a new array by spreading elements from the original array. Pros: concise and efficient. Cons: requires JavaScript 2015 or later for support.
4. **`for` loop and `push()`**: This method pushes all elements from the original array onto a new array using a `for` loop. Pros: can be used with arrays of any type, including nested arrays. Cons: less concise and may have performance overhead due to the use of a `for` loop.

**Library usage**

None of the test cases explicitly uses a JavaScript library.

**Special JS features or syntax**

The spread operator (`...`) is used in one of the test cases, which requires JavaScript 2015 or later for support. The other test cases do not use any special features or syntax.

**Other alternatives**

There are additional ways to create a shallow copy of an array in JavaScript, including:

1. Using `Array.from()`: This method creates a new array by copying elements from the original array.
2. Using a `forEach()` loop: This method pushes all elements from the original array onto a new array using a `forEach()` loop.

These alternatives are not included in the test cases provided.

I hope this explanation helps! Let me know if you have any further questions.

Related benchmarks:

shallow copy of array (version: 0)

Comparing performance of: slice vs push-apply vs the ...operator vs for-push vs concat

Created: 4 years ago by: Guest

Jump to the latest result

slice

push-apply

the ...operator

for-push

concat

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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