Benchmark: fill vs for loop

Tests:

fill
const arr = new Array(100000).fill().map((_,i) => (i))
for
const arr = []; for (let i = 0; i < 100000; i++) { arr.push(i); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
fill
for

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/104.0.0.0 Safari/537.36

Browser/OS: Chrome 104 on Windows

View result in a separate tab

Test name	Executions per second
fill	510.9 Ops/sec
for	830.6 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to explain the benchmark and its various aspects.

**What is being tested?**

The benchmark compares two approaches to populate an array with 100,000 elements: using the `Array.prototype.fill()` method followed by `map()`, and using a traditional `for` loop.

**Options compared**

There are two options being compared:

1. **fill**: This option uses the `Array.prototype.fill()` method followed by `map()` to populate the array.
2. **for**: This option uses a traditional `for` loop to iterate over an index range and push elements onto the array.

**Pros and Cons of each approach**

**Fill:**

Pros:

* More concise and expressive code
* Can be faster due to the optimized implementation of `Array.prototype.fill()` in modern browsers
* Less prone to errors, as it's a single method call

Cons:

* May not work correctly in older browsers that don't support `fill()`
* Requires a second method call to create an array, which may incur additional overhead

**For:**

Pros:

* Works correctly in all browsers and environments
* Allows for more fine-grained control over the iteration process
* No dependency on modern browser features

Cons:

* More verbose code
* May be slower due to the overhead of the loop and push operations

**Other considerations**

Both approaches have their trade-offs, but the `fill()` method is generally preferred due to its conciseness and optimized implementation. However, if you need to support older browsers or require more control over the iteration process, the traditional `for` loop may be a better choice.

**Library usage**

The benchmark uses the `Array.prototype.fill()` method, which is a part of the JavaScript standard library. The `fill()` method is used to set all elements of an array to a specified value, in this case, creating an array filled with undefined values. The subsequent call to `map()` is used to transform each element of the array into its index.

**Special JS feature or syntax**

The benchmark uses JavaScript's array methods and loops. No special features or syntax are required for this benchmark, making it accessible to a wide range of developers.

**Alternatives**

Other alternatives for populating an array include:

* Using `Array.from()` method, which creates a new array from an iterable.
* Using the spread operator (`[...new Array(100000)]`) to create an array filled with undefined values.
* Using a library like Lodash, which provides a `fill` function.

However, these alternatives may not be suitable for all use cases or environments, and the traditional `for` loop remains a reliable option.

Related benchmarks:

fill vs for loop (version: 0)

fill vs for

Comparing performance of: fill vs for

Created: 2 years ago by: Guest

Jump to the latest result

fill

for

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):