Benchmark: Reduce and Spread vs. Foreach and Mutate 2

Script Preparation code:

var objectsArray = Array(1000).fill(() => {
  const key = Math.random().toString(36).substring(2, 5);
  const value = Math.random().toString(36).substring(2, 5);
  return {[key]: value};
});

Tests:

Reduce and Spread
var combined = objectsArray.reduce((memo, obj) => ({...memo, ...obj}), {});
ForEach and Mutate (for .. in loop)
var combined = {} objectsArray.forEach(obj => { for (key in obj) { combined[key] = obj[key]; } });
Mutate with Object.assign
var combined = Object.assign(...objectsArray)
Foreach and Mutate (Object.assign)
var combined = {} objectsArray.forEach(obj => Object.assign(combined, obj));
Reduce Mutate
var combined = objectsArray.reduce((memo, obj) => Object.assign(memo, obj), {});

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Reduce and Spread
ForEach and Mutate (for .. in loop)
Mutate with Object.assign
Foreach and Mutate (Object.assign)
Reduce Mutate

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 dive into the world of JavaScript benchmarks.

The provided JSON represents a benchmark named "Reduce and Spread vs. Foreach and Mutate 2". This benchmark compares four different approaches to merge an array of objects:

1. Reduce and Spread
2. ForEach and Mutate (using `for` loop)
3. Mutate with `Object.assign`
4. Foreach and Mutate (using `Object.assign`)

Now, let's break down each approach:

**Reduce and Spread**

This method uses the `reduce()` function to merge the objects in the array. The spread operator (`...`) is used to concatenate the properties of each object into a single object.

Pros: Efficient use of array methods and concise code.
Cons: May have performance overhead due to the creation of intermediate objects.

**ForEach and Mutate (using for loop)**

This method uses a `for` loop to iterate over the array of objects. For each iteration, it uses the spread operator (`...`) to concatenate the properties of the current object with the result object.

Pros: Easy to understand and modify.
Cons: May have performance overhead due to the use of a `for` loop and explicit property concatenation.

**Mutate with Object.assign**

This method uses the `Object.assign()` function to merge the objects in the array. The first argument is the target object, which is initialized as an empty object.

Pros: Efficient use of built-in functions.
Cons: May have performance overhead due to the creation of intermediate objects.

**Foreach and Mutate (using Object.assign)**

This method uses a `for...of` loop to iterate over the array of objects. For each iteration, it uses `Object.assign()` to merge the properties of the current object with the result object.

Pros: Efficient use of built-in functions.
Cons: May have performance overhead due to the creation of intermediate objects.

Now, let's talk about the libraries used in this benchmark:

* None

The only library mentioned is not explicitly stated, but it can be inferred that the benchmark uses the `Array` and `Object` prototypes, which are part of the JavaScript standard library.

Some special JS features used in this benchmark include:

* Spread operator (`...`)
* Rest parameters (not explicitly used, but implied by the spread operator)
* Arrow functions (`=>`)
* Object methods like `reduce()`, `forEach()`, and `assign()`

Other considerations:

* The benchmark is run on a desktop platform with Firefox 93, which may have specific optimization flags or features that affect performance.
* The test results are reported in terms of executions per second, which is an interesting metric for comparing the performance of different algorithms.

Alternatives to these approaches include:

* Using `Array.prototype.reduce()` method with a custom merge function
* Using a library like Lodash to perform the merge operations
* Using a data structure like a graph or tree to represent the objects and their relationships

Overall, this benchmark provides a useful comparison of different approaches to merging arrays of objects in JavaScript. By analyzing the pros and cons of each approach, developers can choose the most efficient and readable solution for their specific use case.

Latest run results:

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

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:93.0) Gecko/20100101 Firefox/93.0

Browser/OS: Firefox 93 on Ubuntu

View result in a separate tab

Test name	Executions per second
Reduce and Spread	4155.5 Ops/sec
ForEach and Mutate (for .. in loop)	1259.8 Ops/sec
Mutate with Object.assign	15010.8 Ops/sec
Foreach and Mutate (Object.assign)	7108.1 Ops/sec
Reduce Mutate	6919.2 Ops/sec

Related benchmarks:

Reduce and Spread vs. Foreach and Mutate 2 (version: 0)

Comparing performance of: Reduce and Spread vs ForEach and Mutate (for .. in loop) vs Mutate with Object.assign vs Foreach and Mutate (Object.assign) vs Reduce Mutate

Created: 3 years ago by: Guest

Jump to the latest result

Reduce and Spread

ForEach and Mutate (for .. in loop)

Mutate with Object.assign

Foreach and Mutate (Object.assign)

Reduce Mutate

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):