Benchmark: reduce/spread4 - MeasureThat.net

Script Preparation code:

const size = 1000;

var items = [];
for (let i = 0; i < size; i += 1) {
    items.push({
        id: `item-${i}`,
        value: `Item ${i}`
    });
}

Tests:

spread
const results = items.reduce((list, cur) => { return { ...list, [cur.id]: cur.value }; }, {});
non-spread
const results = items.reduce((list, cur) => { const updatedItems = list; updatedItems[cur.id] = cur.value; return updatedItems; }, {});

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
spread
non-spread

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.77 Safari/537.36

Browser/OS: Chrome 91 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
spread	12.1 Ops/sec
non-spread	4408.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Definition**

The provided JSON represents a benchmark named `reduce/spread4`. This benchmark is designed to measure the performance difference between two approaches when reducing an array in JavaScript: using the spread operator (`...`) and not using it.

**Script Preparation Code**

The script preparation code creates an array of objects with unique IDs and values, which will be used as input for the benchmark:
```javascript
const size = 1000;
var items = [];
for (let i = 0; i < size; i += 1) {
    items.push({
        id: `item-${i}`,
        value: `Item ${i}`
    });
}
```
This code creates an array of 1000 objects, where each object has a unique `id` and a corresponding `value`.

**Html Preparation Code**

The HTML preparation code is empty in this case, which means that no HTML code is executed before running the benchmark.

**Individual Test Cases**

There are two test cases:

1. **"spread"`**: This test case uses the spread operator (`...`) to update the array:
```javascript
const results = items.reduce((list, cur) => {
  return { ...list, [cur.id]: cur.value };
}, {});
```
This approach creates a new object with the updated key-value pairs.

2. **"non-spread"`**: This test case updates the array without using the spread operator:
```javascript
const results = items.reduce((list, cur) => {
  const updatedItems = list;
  updatedItems[cur.id] = cur.value;
  return updatedItems;
}, {});
```
This approach modifies the original array by updating its properties directly.

**Pros and Cons**

* **Spread Operator (`...`)**:
	+ Pros: More concise, easier to read, and less error-prone.
	+ Cons: Can be slower due to object creation overhead.
* **Non-spread operator**:
	+ Pros: Faster execution since it avoids creating a new object.
	+ Cons: Can be harder to read and maintain due to the need for explicit property updates.

**Other Considerations**

The choice between using the spread operator and not using it depends on the specific use case, performance requirements, and personal preference. If readability and conciseness are crucial, the spread operator might be a better choice. However, if raw performance is essential, the non-spread approach might be preferred.

**Library and Special JS Feature**

There is no explicit library mentioned in the benchmark definition. The JavaScript standard library is used to implement the `reduce()` method.

No special JavaScript features or syntax are explicitly mentioned. If you're interested in exploring other features like `let` and `const` declarations, hoisting, or closures, I can provide information on those topics as well!

**Alternative Approaches**

Other alternatives for reducing an array in JavaScript include:

1. **Using `forEach()`**: Instead of using `reduce()`, you can use the `forEach()` method to iterate over the array and update its properties.
```javascript
items.forEach((item) => {
  items[item.id] = item.value;
});
```
2. **Using a `for` loop**: You can use a traditional `for` loop to iterate over the array and update its properties.
```javascript
const results = {};
for (let i = 0; i < items.length; i++) {
  results[items[i].id] = items[i].value;
}
```
Keep in mind that these alternatives might have different performance characteristics compared to using `reduce()` or the spread operator.

Related benchmarks:

reduce/spread4 (version: 3)

Comparing performance of: spread vs non-spread

Created: 3 years ago by: Registered User

Jump to the latest result

spread

non-spread

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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