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};});var combined = objectsArray.reduce((memo, obj) => ({memo, obj}), {});var combined = {}objectsArray.forEach(obj => { for (key in obj) { combined[key] = obj[key]; }});var combined = Object.assign(objectsArray)var combined = {}objectsArray.forEach(obj => Object.assign(combined, obj));--enable-precise-memory-info flag.
| Test case name | Result |
|---|---|
| Reduce and Spread | |
| ForEach and Mutate (for .. in loop) | |
| Mutate with Object.assign | |
| Foreach and Mutate (Object.assign) |
| 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 |
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:
reduce() method to combine all objects in the array into one object, and then uses the spread operator (...) to expand it.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.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.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.
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.
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.
Object.assign() functionForeach 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.
Object.assign() functionLibraries and Special Features
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.
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.
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.
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.
