Benchmark: spread vs mutation vs Object.assign for reduce callback for objects

Tests:

with spread operator
const range = (from, to) => { const output = [] for(var x = from; x < to; x++){ output.push({x, y: x, z: x}) } return output } range(0, 10).reduce((acc, obj) => { return { ...acc, ...obj } }, {})
with mutation
const range = (from, to) => { const output = [] for(var x = from; x < to; x++){ output.push({x, y: x, z: x}) } return output } range(0, 10).reduce((acc, obj) => { for (const key of Object.keys(obj)) { acc[key] = obj[key] } return acc }, {})
with object assign
const range = (from, to) => { const output = [] for(var x = from; x < to; x++){ output.push({x, y: x, z: x}) } return output } range(0, 10).reduce((acc, obj) => { return Object.assign(acc, obj) }, {})

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
with spread operator
with mutation
with object assign

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**Benchmark Definition**

The website provides a JSON object that defines the benchmark. In this case, it's comparing three approaches to merge objects in an array using the `reduce` method:

1. **Spread Operator (`...`)**: This approach uses the spread operator to merge two objects into one.
2. **Mutation**: This approach iterates over the keys of each object and assigns the corresponding value from the second object to a new property on an accumulator object.
3. **Object Assign (`Object.assign()`)**: This approach uses the `Object.assign()` method to merge two objects.

**Comparison**

The benchmark is comparing the performance of these three approaches on a simple test case:

* The test case generates an array of objects with three properties each (x, y, and z) using the `range` function.
* The `reduce` method is used to iterate over this array and merge each object into an accumulator object.

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

1. **Spread Operator (`...`)**
	* Pros: concise, readable, efficient (since it doesn't require explicit loop iterations).
	* Cons: may not be suitable for very large objects or complex merge logic.
2. **Mutation**
	* Pros: can be more control-oriented and flexible than the spread operator approach.
	* Cons: may be slower due to the need for explicit loop iterations and key access.
3. **Object Assign (`Object.assign()`)**
	* Pros: efficient and straightforward, but may require additional setup (e.g., converting objects to arrays).
	* Cons: can be less readable than other approaches, especially for complex merge logic.

**Library and Features**

There are no specific libraries mentioned in the benchmark definition. However, it's worth noting that `Object.assign()` is a built-in method in JavaScript, so no additional library is required.

No special JavaScript features or syntax are used in this benchmark.

**Alternatives**

If you're interested in exploring alternative approaches to merging objects, here are a few examples:

1. **Using `lodash`**: You can use the `lodash.merge()` function, which provides a robust and flexible way to merge objects.
2. **Implementing a custom merger function**: You could write a custom function that takes two objects as input and returns a merged object. This approach would allow you to tailor the merging behavior to your specific needs.
3. **Using `JSON.parse()` and `JSON.stringify()`**: You can use these methods to merge objects by converting them to JSON strings, concatenating the strings, and then parsing the result back into an object.

Keep in mind that these alternatives may have different performance characteristics or readability implications compared to the original benchmark approaches.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.114 Safari/537.36

Browser/OS: Chrome 91 on Mac OS X 10.14.6

View result in a separate tab

Test name	Executions per second
with spread operator	713902.4 Ops/sec
with mutation	374179.9 Ops/sec
with object assign	490678.1 Ops/sec

Related benchmarks:

spread vs mutation vs Object.assign for reduce callback for objects (version: 0)

Comparing performance of: with spread operator vs with mutation vs with object assign

Created: 3 years ago by: Guest

Jump to the latest result

with spread operator

with mutation

with object assign

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):