Benchmark: property assign vs spread operator (iterated)

Tests:

property assignment
var params = { b:"hello", c: true, d:7 }; for (var i = 0; i < 100; i++) { params[i] = i; }
spread operator
var params = { b:"hello", c: true, d:7 }; for (var i = 0; i < 100; i++) { params = { [i]: i, ...params}; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
property assignment
spread operator

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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I'll break down the benchmark definition and test cases, explaining what's being tested, the pros and cons of each approach, and other considerations.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmark on MeasureThat.net. The benchmark is defined as follows:

* "Name": "property assign vs spread operator (iterated)"
* "Description": null
* "Script Preparation Code": null
* "Html Preparation Code": null

This benchmark compares the performance of two approaches: property assignment and using the spread operator in an iterative loop.

**Test Cases**

There are two test cases:

1. **Property Assignment**
```javascript
var params = { b:"hello", c:true, d:7 };
for (var i = 0; i < 100; i++) {
  params[i] = i;
}
```
This test case measures the performance of assigning properties to an object using a traditional `params[i] = i` approach.

2. **Spread Operator**
```javascript
var params = { b:"hello", c:true, d:7 };
for (var i = 0; i < 100; i++) {
  params = {[i]: i, ...params};
}
```
This test case measures the performance of using the spread operator (`...params`) to assign new properties to an object in a loop.

**What's being tested?**

The benchmark is testing the performance of two different approaches:

* Property assignment: Assigning properties directly to an object.
* Spread operator: Using the spread operator to add new properties to an existing object.

**Pros and Cons of each approach**

1. **Property Assignment**
	* Pros:
		+ Easy to understand and implement.
		+ Can be more efficient for small objects, as it avoids creating a new object and copying properties.
	* Cons:
		+ Can lead to slower performance in large loops due to repeated assignments.
2. **Spread Operator**
	* Pros:
		+ Efficient for large objects, as it creates a new object with the updated properties without repeating assignments.
	* Cons:
		+ May have overhead due to creating and copying objects.

**Other considerations**

The benchmark does not take into account other factors that might affect performance, such as:

* Object size: The spread operator might perform better for larger objects.
* JavaScript engine optimizations: Different engines may optimize one approach over the other.
* Memory allocation: Repeated assignments can lead to more memory allocations than using the spread operator.

**Library and special JS feature**

There is no library mentioned in the benchmark definition. However, the use of the spread operator (`...params`) relies on a JavaScript feature introduced in ECMAScript 2018 (ES2018). If you're running an older version of JavaScript, this syntax might not be supported.

**Alternatives**

If you want to explore alternative approaches or test other performance scenarios, consider these alternatives:

* Use `Object.assign()` instead of spread operator.
* Compare performance with and without using a loop; the benchmark currently uses a simple iterative loop.
* Test different object sizes or shapes to see how they affect performance.

Keep in mind that this is a simplified benchmark, and real-world scenarios might involve more complex optimizations or edge cases.

Related benchmarks:

property assign vs spread operator (iterated) (version: 0)

Comparing performance of: property assignment vs spread operator

Created: 6 years ago by: Registered User

Jump to the latest result

property assignment

spread operator

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):