Benchmark: Array fill vs for i loop

Script Preparation code:

var iterations = 10000;
var arrayTest = new Array(iterations);

Tests:

for
for (i = 0; i < iterations; i++) { arrayTest[i] = 0 }
fill and foreach
arrayTest.fill(0)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
fill and foreach

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:132.0) Gecko/20100101 Firefox/132.0

Browser/OS: Firefox 132 on Windows

View result in a separate tab

Test name	Executions per second
for	15948.9 Ops/sec
fill and foreach	126133.3 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Description**

The provided JSON represents a benchmarking test for comparing two approaches to fill an array with zeros: using a `for` loop and using the `fill()` method in combination with a `forEach` loop.

**Options Compared**

Two options are being compared:

1. **For Loop**: Using a traditional `for` loop to iterate over an array and assign a value (in this case, zero) to each element.
2. **Fill() + Foreach**: Using the `fill()` method to fill the entire array with a single value (zero), followed by using a `forEach` loop to iterate over the array.

**Pros and Cons of Each Approach**

1. **For Loop**
	* Pros: Generally considered more explicit and easier to understand for some developers.
	* Cons: Can be slower due to the overhead of incrementing an index variable, checking bounds, and updating the value.
2. **Fill() + Foreach**
	* Pros: Often faster since it avoids the overhead of a loop counter and index management. It also provides a concise way to fill an array with a single operation.
	* Cons: May be less intuitive for some developers who are not familiar with the `fill()` method.

**Library Used**

The benchmark uses the JavaScript Array prototype, specifically the `fill()` and `forEach` methods, which are built-in features of the language. No external libraries are required for this test.

**Special JS Feature/Syntax**

No special JavaScript feature or syntax is being tested in this benchmark. The focus is on comparing two conventional approaches to filling an array with zeros.

**Other Alternatives**

If you're interested in exploring alternative approaches, consider the following:

* Using `Array.prototype.map()` instead of a loop: While not exactly what's being compared here, using `map()` could provide similar performance characteristics as the `fill()` + `forEach` approach.
* Using a library like Lodash or Underscore.js for array operations: These libraries often provide optimized implementations of various array methods that might offer better performance than built-in JavaScript methods.

Now, when evaluating benchmarking results, it's essential to consider factors beyond just raw execution speed, such as code readability, maintainability, and potential errors.

Related benchmarks:

Array fill vs for i loop (version: 0)

People tend to use array fil and then foreach, we know foreach is faster than a for loop, but is it also faster if you use array fill first?

Comparing performance of: for vs fill and foreach

Created: 2 years ago by: Guest

Jump to the latest result

for

fill and foreach

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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