Benchmark: slice+push vs concat

Tests:

slice+push
const testArray = [1, 2, 3]; const newTestArray = testArray.slice(); newTestArray.push(4);
concat
const testArray = [1, 2, 3]; const newTestArray = testArray.concat(4);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice+push
concat

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.135 Safari/537.36

Browser/OS: Chrome 84 on Windows

View result in a separate tab

Test name	Executions per second
slice+push	32372000.0 Ops/sec
concat	3339205.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested on the provided JSON.

**Benchmark Definition**

The benchmark measures the performance difference between two approaches: `slice()` and `push()` for creating a new array, versus using `concat()` to concatenate an existing array with a single element.

**Options Compared**

There are three options being compared:

1. **`slice()` + `push()`**: This approach creates a new array by copying the original array using `slice()`, and then adds a new element using `push()`.
2. **`concat()`**: This approach concatenates the existing array with a single element using `concat()`.

**Pros and Cons**

Here are some pros and cons of each approach:

* **`slice()` + `push()`**:
	+ Pros: Efficient for small arrays, as it only copies a subset of elements.
	+ Cons: Can be slower for larger arrays, as it involves more function calls and array copying.
* **`concat()`**:
	+ Pros: Simple and efficient, but can lead to unnecessary memory allocations.
	+ Cons: Can be slower than `slice()` + `push()`, especially for large arrays.

**Library Usage**

There is no explicit library usage mentioned in the benchmark definition. However, it's worth noting that some browsers may have optimized implementations of these functions or additional libraries that might affect performance.

**Special JS Feature/Syntax**

The benchmark uses JavaScript syntax specific to modern browsers, such as `const` declarations and arrow functions (`=>`). These features are not unique to the browser and are part of the standard language specification. However, their usage in this context may affect performance depending on the specific browser implementation.

**Other Considerations**

When interpreting these results, it's essential to consider factors like:

* Array size: The benchmark only tests small arrays (e.g., `[1, 2, 3]`). Results might differ for larger arrays.
* Browser version and platform: Different browsers may optimize or implement these functions differently, affecting performance.
* Other factors influencing execution time: Memory allocation, cache locality, and instruction-level parallelism can also impact the results.

**Alternatives**

If you're interested in exploring alternative approaches, consider the following:

* Using `Array.prototype.slice.call()` instead of `slice()`
* Employing a library like Lodash's `cloneDeep` or a similar utility to create a deep copy
* Investigating hand-rolled array operations using bitwise operators and indexing

Related benchmarks:

slice+push vs concat (version: 0)

Comparing performance of: slice+push vs concat

Created: 4 years ago by: Guest

Jump to the latest result

slice+push

concat

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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