Benchmark: Spread vs Push in Reduce

Script Preparation code:

var xs = ["b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"]

Tests:

Push
xs.reduce((acc, x) => { acc.push(x); return acc; }, ["a"]);
Spread
xs.reduce((acc, x) => [...acc, x], ["a"]);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Push
Spread

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and its test cases.

**Benchmark Overview**

The benchmark measures the performance difference between using the `push()` method versus the spread operator (`...`) when reducing an array in JavaScript.

**Test Cases**

There are two test cases:

1. **Push**: This test case uses the `reduce()` method with the `push()` method inside the callback function.
```javascript
xs.reduce((acc, x) => {
  acc.push(x);
  return acc;
}, ["a"]);
```
2. **Spread**: This test case uses the `reduce()` method with the spread operator (`...`) to create a new array and add elements to it.
```javascript
xs.reduce((acc, x) => [...acc, x], ["a"]);
```
**Options Compared**

The benchmark compares two approaches:

1. **Push Method**: The `push()` method is used to add elements to the accumulator array (`acc`).
2. **Spread Operator**: The spread operator (`...`) is used to create a new array and add elements to it.

**Pros and Cons of Each Approach**

1. **Push Method**:
	* Pros:
		+ Typically faster, as it only requires updating the index of the `push()` method.
		+ May be more cache-friendly due to the smaller memory allocation.
	* Cons:
		+ Requires an additional loop iteration, which can increase overhead.
2. **Spread Operator**:
	* Pros:
		+ Can create a new array with a single operation, reducing overhead.
		+ May be more readable and concise for some use cases.
	* Cons:
		+ Creates a new array, which can lead to increased memory allocation and garbage collection.

**Library and Special JS Feature**

In this benchmark, no special JavaScript features or libraries are used. The test cases only rely on standard JavaScript functionality.

**Other Alternatives**

If you were to rewrite the benchmark with different approaches, some alternatives could include:

1. **Using `concat()`**: Instead of using `push()`, you could use `concat()` to concatenate arrays.
```javascript
xs.reduce((acc, x) => acc.concat(x), ["a"]);
```
2. **Using `Array.prototype.fill()`**: You could use `fill()` to create a new array filled with the accumulator value.
```javascript
xs.reduce((acc, x) => Array(acc.length + 1).fill(x), ["a"]);
```
Keep in mind that these alternatives might change the benchmark's results or behavior.

Related benchmarks:

Spread vs Push in Reduce (version: 0)

Comparing performance of: Push vs Spread

Created: 3 years ago by: Guest

Jump to the latest result

Push

Spread

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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