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 | 1924392.4 Ops/sec |
Using Object.assign | 4474362.5 Ops/sec |
Let's break down the provided benchmark and explain what's being tested.
What is being tested?
The provided JSON represents two test cases, each testing the performance of JavaScript objects with varying methods: the spread operator (...
) and Object.assign()
. The benchmark aims to compare these two approaches in creating new objects by combining existing ones.
Options compared:
...
): This syntax is used to create a new object by spreading the properties of an existing object into a new object.Object.assign()
: This method is used to copy all enumerable own properties from one or more source objects to a target object.Pros and Cons:
...
):...[1, 2, 3]
)Object.assign()
:Library:
Neither test case relies on any external libraries. The Object.assign()
method is a built-in JavaScript function.
Special JS Feature/Syntax:
There are no special features or syntaxes being tested here, as both test cases use standard JavaScript constructs.
Other Considerations:
When choosing between the spread operator and Object.assign()
, consider the following factors:
Object.assign()
might be a better fit.Alternatives:
For creating new objects by combining existing ones, other approaches include:
for...in
or Object.keys()
.+
operator to concatenate two objects (not recommended due to potential performance issues).It's worth noting that the spread operator has become increasingly popular and efficient in modern JavaScript, making it a preferred choice for many developers.