Benchmark: Concat vs push(...) for large arrays 223123

Script Preparation code:

window.top.tests = {control:[], concat:[], spread:[]};
window.test = (new Array(10)).fill(null);
window.cutoff = 5000;

Tests:

Control (for push)
for (let element of window.test) window.top.tests.control.push(element);
Concat
window.top.tests.concat = window.top.tests.concat.concat(window.test);
Spread
window.top.tests.spread.push(...window.test);
Spread 2
window.top.tests.spread = [window.top.tests.spread, ...window.test];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Control (for push)
Concat
Spread
Spread 2

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 months 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

Browser/OS: Chrome 133 on Windows

View result in a separate tab

Test name	Executions per second
Control (for push)	414745.2 Ops/sec
Concat	744.3 Ops/sec
Spread	1555968.0 Ops/sec
Spread 2	53699.5 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):

LLMs can make mistakes. Check important info.

The benchmark described compares the performance of different methods for appending elements to an array in JavaScript, specifically focusing on a large array. The methods being evaluated include traditional array push with a loop, array concatenation using the `concat` method, and the spread operator for array operations.

### Methods Compared

1. **Control (for push)**:
   - **Implementation**: The benchmark computes the total by appending elements from the `window.test` array using a `for..of` loop and the `push` method.
   - **Pros**:
     - Straightforward and intuitive to understand.
     - Efficient for small to moderate-sized arrays.
   - **Cons**:
     - Can be slower compared to bulk operations when dealing with large arrays due to individual element processing.
   
2. **Concat**:
   - **Implementation**: Uses `concat` to combine the existing array with `window.test` in a way that effectively creates a new array.
   - **Pros**:
     - Clear syntax for combining arrays.
     - Keeps the original arrays intact (non-destructive).
   - **Cons**:
     - Performance can degrade with large arrays because it creates a new array and can lead to increased memory usage. Each call to `concat` can become expensive as array sizes grow.

3. **Spread**:
   - **Implementation**: Uses the spread operator (`...`) to efficiently append elements of `window.test` to `window.top.tests.spread`.
   - **Pros**:
     - Very concise and clear syntax.
     - Generally performs well, especially with larger datasets, as it can leverage optimizations in modern JavaScript engines.
   - **Cons**:
     - Can lead to performance issues in extremely large datasets if the engine does not handle spread operations efficiently. However, modern JavaScript engines are typically optimized for this use case.

4. **Spread 2**:
   - **Implementation**: Here, it constructs a new array by using the spread operator along with `window.top.tests.spread`.
   - **Pros**:
     - Focuses on immutability, creating new data structures without altering the existing one.
     - Offers clarity and flexibility in handling arrays.
   - **Cons**:
     - Similar to the simple spread case, large datasets could lead to poor performance if not handled well by the browser's JavaScript engine.

### Performance Insights

According to the benchmark results:

- The **Spread** method yielded the highest number of executions per second, suggesting it was the most efficient for appending elements to a large array in this particular test scenario.
- The **Control (for push)** method showed decent performance, but it was considerably lower than the spread method.
- The **Spread 2** method performed acceptably, but not as well as the primary spread approach.
- The **Concat** method fell significantly behind in performance, indicating that it may not be the best choice for high-frequency array operations.

### Alternative Considerations

While the benchmark focuses on these methods, there are other alternatives to manipulate arrays in JavaScript:

1. **Array.prototype.unshift()**: Adds elements to the beginning of an array. It could be interesting to measure how this compares to the other methods.

2. **Array.prototype.splice()**: Allows inserting elements at any position in the array but is typically slower due to it having to shift array elements.

3. **Using Typed Arrays**: Typed arrays may offer better performance for numerical data, but they lack the flexibility of regular arrays.

4. **Dedicated libraries (e.g., Lodash)**: Libraries like Lodash offer utility functions for manipulating collections and arrays, potentially offering additional performance optimizations.

Ultimately, the choice of array manipulation method can depend heavily on context: the size of the data, frequency of operations, and whether the array's original order or content matters to the implementation.

Related benchmarks:

Concat vs push(...) for large arrays 223123 (version: 1)

Comparing the various ways to append to a large array

Comparing performance of: Control (for push) vs Concat vs Spread vs Spread 2

Created: 2 months ago by: Guest

Jump to the latest result

Control (for push)

Concat

Spread

Spread 2

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 2 months ago):