const firstObject = { sampleData: 'Hello world' }const secondObject = { moreData: 'foo bar' }const finalObject = { firstObject, secondObject};const firstObject = { sampleData: 'Hello world' }const secondObject = { moreData: 'foo bar' }const finalObject = Object.assign({}, firstObject, secondObject);--enable-precise-memory-info flag.
| Test case name | Result |
|---|---|
| Using the spread operator | |
| Using Object.assign |
| Test name | Executions per second |
|---|---|
| Using the spread operator | 2997493.0 Ops/sec |
| Using Object.assign | 3082945.2 Ops/sec |
Let's dive into the world of JavaScript microbenchmarks.
Benchmark Purpose and Description
The provided benchmark measures the performance difference between using the spread operator (...) and Object.assign (with an immutable object) when merging two objects in JavaScript. The test case is designed to compare these two approaches on a consistent dataset, ensuring that any observed differences are due to the specific implementation details of each method.
Options Compared
Two options are being compared:
...): This syntax was introduced in ECMAScript 2018 (ES9) and allows for easy object spreading using the three dots ... before an object.Object.assign() with immutable objects: The Object.assign() method takes multiple arguments and merges them into a single object, creating new properties for each object being merged.Pros and Cons of Each Approach
...)Pros:
Cons:
Object.assign() with immutable objectsPros:
Cons:
Library/Functionality Used
In this benchmark, Object.assign() is being compared. This is a built-in JavaScript function that has been part of the language since ECMAScript 2009.
Special JS Features/Syntax
There are no special JavaScript features or syntaxes being tested in this benchmark.
Alternative Approaches
Other alternatives for merging objects include:
Object.create() and then assigning properties to create a new object_merge) or Ramda (merge)For most use cases, the spread operator (...) has become a popular choice due to its concise syntax and immutability benefits. However, when performance is critical or older browsers are required, Object.assign() with immutable objects remains a viable option.
Keep in mind that this benchmark specifically compares these two approaches on an immutable object merge scenario. Depending on the use case, other merging methods may be more suitable.
When preparing benchmarks, consider factors such as:
