Benchmark: Array.prototype.slice vs spread operator large arrays

Tests:

Array.prototype.slice large
var params = Array.from({length: 10000}, () => 1) var other = params.slice();
spread operator large
var params = Array.from({length: 10000}, () => 1) var other = [ ...params ]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.prototype.slice large
spread operator large

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 13 days ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser/OS: Chrome 135 on Windows

View result in a separate tab

Test name	Executions per second
Array.prototype.slice large	4780.3 Ops/sec
spread operator large	4718.1 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 14 days ago):

LLMs can make mistakes. Check important info.

### Benchmark Overview

The benchmark titled **"Array.prototype.slice vs spread operator large arrays"** aims to compare the performance of two methods for copying large arrays in JavaScript: the traditional `Array.prototype.slice()` method and the modern ES6 spread operator (`[...]`).

### Test Cases Description

1. **Test Case: Array.prototype.slice large**
   - **Benchmark Definition:** 
     ```javascript
     var params = Array.from({length: 10000}, () => 1);
     var other = params.slice();
     ```
   - **Explanation:** 
     This test case creates a large array (`params`) filled with 10,000 elements, all set to 1. It then uses the `slice()` method to create a shallow copy of that array (`other`). The `slice()` method is well-established in JavaScript and allows for copying parts of an array. When called without arguments, it copies the entire array.

2. **Test Case: spread operator large**
   - **Benchmark Definition:** 
     ```javascript
     var params = Array.from({length: 10000}, () => 1);
     var other = [ ...params ];
     ```
   - **Explanation:** 
     Similarly, this test also creates an array with 10,000 elements of 1. However, it uses the spread operator (`[...]`) to create a new array. The spread operator is a concise syntax introduced in ES6 that allows for the expansion of elements from an iterable (in this case, the array `params`) into a new array.

### Performance Results

The results indicate the **Executions Per Second** for each test. Here are the numbers from the benchmark:

- **Array.prototype.slice large:** 3606.10 executions per second
- **Spread operator large:** 3586.52 executions per second

### Pros and Cons

#### Array.prototype.slice

**Pros:**
- **Compatibility:** It is widely supported in all JavaScript environments, including older versions, making it a safe choice for projects that need to support legacy browsers.
- **Clarity:** Some developers may find it easier to understand and maintain, especially if they are not familiar with the ES6 syntax.

**Cons:**
- **Verbosity:** Slightly longer syntax, which may contribute to reduced readability in larger contexts.
- **Performance:** In some instances (depending on the environment), it may be less performant compared to the spread operator.

#### Spread Operator

**Pros:**
- **Conciseness:** The spread syntax is cleaner and easier to read, making the code more expressive.
- **New Features:** It allows for merging or interpolating arrays and objects in an elegant fashion.

**Cons:**
- **Browser Support:** While most modern browsers support the spread operator, legacy browsers may not, which is a consideration for projects that need extensive compatibility.
- **Slightly Higher Overhead:** In certain scenarios and with very large datasets, the spread operator might introduce a bit more overhead in performance compared to `slice()`.

### Other Considerations

- **Memory Consumption:** Both techniques create a shallow copy of the array, meaning that if the array contains references to objects, those objects will not be duplicated; only the references will be copied.
- **Use Cases:** Choosing between the two can depend on the specific use case. For copying entire arrays, both methods work well, but understanding the nuances in performance and readability might help in making a decision.

### Alternatives

Other alternatives for copying arrays in JavaScript include:

- **Array.from():** This method can also be used to create a new array instance from an existing array-like or iterable object.
  
  ```javascript
  var other = Array.from(params);
  ```

- **Concat Method:** Using the `concat()` method to copy an array by combining it with an empty array:
  
  ```javascript
  var other = [].concat(params);
  ```

Each of these methods (like `Array.from` and `concat`) has its pros and cons regarding performance and readability as well. Ultimately, the choice depends on the specific scenario, codebase requirements, and developer preferences.

Related benchmarks:

Array.prototype.slice vs spread operator large arrays (version: 1)

Compare the new ES6 spread operator with the traditional slice() method

Comparing performance of: Array.prototype.slice large vs spread operator large

Created: 15 days ago by: Guest

Jump to the latest result

Array.prototype.slice large

spread operator large

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 14 days ago):