Benchmark: Reduce Destructuring vs Assertion

Script Preparation code:

var arr = Array(10_000).fill(0);

Tests:

{ ...acc, [x]: true }
arr.reduce((acc, x) => ({ ...acc, [x]: true }), {})
acc[x] = true;
arr.reduce((acc, x) => { acc[x] = true; return acc; }, {})

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
{ ...acc, [x]: true }
acc[x] = true;

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
{ ...acc, [x]: true }	1763.7 Ops/sec
acc[x] = true;	25718.2 Ops/sec

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 explain what's being tested.

**Benchmark Overview**

The benchmark compares two approaches to reducing a JavaScript object: using the spread operator (`{ ...acc, [x]: true }`) versus assigning directly to an existing key (`acc[x] = true;`).

**Options Compared**

Two options are compared:

1. **Spread Operator**: `{ ...acc, [x]: true }`
2. **Direct Assignment**: `arr.reduce((acc, x) => {\r\n\tacc[x] = true;\r\n    return acc;\r\n}, {})`

**Pros and Cons of Each Approach**

1. **Spread Operator (Destructuring)**
	* Pros:
		+ Can be more concise and readable for simple object updates.
		+ Reduces the need for explicit key management.
	* Cons:
		+ May lead to unexpected behavior if not used carefully, as it can create new properties instead of updating existing ones.
2. **Direct Assignment**
	* Pros:
		+ Can be more efficient in terms of memory allocation and updates, especially for large datasets.
	* Cons:
		+ Requires explicit key management, which can add complexity to the code.

**Other Considerations**

1. **Libraries**: Neither benchmark uses any external libraries.
2. **Special JS Features/Syntax**: Both benchmarks use ES6+ syntax (spread operator and template literals). There are no special JavaScript features or syntax used in this benchmark.

**Alternatives**

If you wanted to modify this benchmark, you could try changing the input size, number of iterations, or even the types of data being processed. Some potential alternatives include:

1. **Increasing Input Size**: Try scaling up the input array size or creating more complex objects with nested structures.
2. **Number of Iterations**: Increase the number of iterations to simulate more realistic scenarios.
3. **Data Types**: Experiment with different data types, such as strings, numbers, or booleans.

Keep in mind that these alternatives would require modifying the benchmark setup and may not yield meaningful results without proper testing and validation.

In summary, this benchmark provides a concise and readable comparison of two object reduction approaches using the spread operator versus direct assignment. It highlights the trade-offs between conciseness and efficiency in JavaScript code.

Related benchmarks:

Reduce Destructuring vs Assertion (version: 0)

Comparing performance of: { ...acc, [x]: true } vs acc[x] = true;

Created: 4 years ago by: Guest

Jump to the latest result

{ ...acc, [x]: true }

acc[x] = true;

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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