Benchmark: Reduce and Spread vs. Foreach and Mutate (for Kafka.js)

Script Preparation code:

var objectsArray = Array(10000).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));

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)

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 microbenchmarks.

The provided JSON represents a benchmark test case for reducing and spreading an array of objects in different ways, specifically using Kafka.js library, which is a JavaScript implementation of Apache Kafka. The test aims to compare the performance of four approaches:

1. **Reduce and Spread**: This approach uses the `reduce()` method to combine all objects in the array into one object, and then uses the spread operator (`...`) to expand it.
2. **ForEach and Mutate (for .. in loop)**: This approach uses a traditional for-each loop with an `in` loop to iterate over each key-value pair of each object in the array, and then mutates the resulting object by assigning its properties.
3. **Mutate with Object.assign**: This approach uses `Object.assign()` to create a new object, and then iterates over each object in the array, passing it as an argument to `Object.assign()`, effectively merging all objects into one.
4. **Foreach and Mutate (Object.assign)**: Similar to the previous approach, but instead of using an `in` loop, it uses the spread operator (`...`) to expand the merged object.

**Pros and Cons**

*   **Reduce and Spread**: This method is concise and efficient as it leverages the optimized implementation of `reduce()` in modern JavaScript. However, if the input array has a large number of objects or deep nested properties, this approach might not be suitable due to potential performance issues.
    *   Pros: Fast, easy to implement
    *   Cons: Potential performance issues for very large inputs, dependency on optimized implementation of `reduce()` function.

*   **ForEach and Mutate (for .. in loop)**: This method is straightforward but can result in poor performance due to the overhead of looping through each key-value pair. Additionally, this approach requires manual property assignment, which can be error-prone.
    *   Pros: Easy to implement, no dependency on optimized implementations
    *   Cons: Slow performance, prone to errors

*   **Mutate with Object.assign**: This method is efficient as it uses `Object.assign()` to create a new object, and then iterates over each object in the array. However, if the objects have deep nested properties or large amounts of data, this approach might not be suitable due to performance issues.
    *   Pros: Efficient, handles complex objects
    *   Cons: Potential performance issues for very large inputs, dependency on `Object.assign()` function

*   **Foreach and Mutate (Object.assign)**: This method is similar to the previous one but uses the spread operator (`...`) to expand the merged object. It has the same pros and cons as the previous approach.
    *   Pros: Handles complex objects efficiently
    *   Cons: Potential performance issues for very large inputs, dependency on `Object.assign()` function

**Libraries and Special Features**

*   **Kafka.js**: Kafka is a JavaScript implementation of Apache Kafka, designed to handle high-throughput, fault-tolerant data processing. It's used in this benchmark test case as the context for array operations.
    *   Purpose: Handle high-throughput, fault-tolerant data processing

**Other Alternatives**

*   **Lodash**: Lodash is a popular JavaScript library that provides various utility functions, including array methods like `reduce()` and `map()`. It can be used to implement the same test cases as this benchmark.
    *   Pros: Provides optimized implementations of array methods
    *   Cons: Additional dependency on the Lodash library

*   **Array.prototype.reduce()**: This is a built-in JavaScript method that reduces an array to a single value. It's optimized for performance and can be used to implement the same test cases as this benchmark.
    *   Pros: Built-in, optimized for performance
    *   Cons: Limited control over iteration order

*   **Array.prototype.forEach()**: This is another built-in JavaScript method that executes a function for each element in an array. It's commonly used with `for` loops but can also be used with arrow functions.
    *   Pros: Built-in, easy to implement
    *   Cons: Slow performance compared to other methods

*   **Object.assign()**: This is a built-in JavaScript method that merges two or more objects into one. It's commonly used when creating new objects from existing ones.
    *   Pros: Efficient for merging objects
    *   Cons: Potential performance issues for very large inputs

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/104.0.0.0 Safari/537.36

Browser/OS: Chrome 104 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Reduce and Spread	2708.0 Ops/sec
ForEach and Mutate (for .. in loop)	8645.0 Ops/sec
Mutate with Object.assign	7506.3 Ops/sec
Foreach and Mutate (Object.assign)	673.8 Ops/sec

Related benchmarks:

Reduce and Spread vs. Foreach and Mutate (for Kafka.js) (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)

Created: 2 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)

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):