Benchmark: Array fill method vs for loop vs push

Tests:

For Loop fill
let arrayTest = new Array(10000000); for (let i = 0; i < arrayTest.length; i++){ arrayTest[i] = 0; }
Array Fill
let arrayTest = new Array(10000000).fill(0);
Push
let arrayTest = []; for (let i = 0; i < 10000000; i++) { arrayTest.push(0); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
For Loop fill
Array Fill
Push

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36

Browser/OS: Chrome 128 on Windows

View result in a separate tab

Test name	Executions per second
For Loop fill	40.4 Ops/sec
Array Fill	20.5 Ops/sec
Push	7.8 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 and explore what's being tested in this particular benchmark.

**Benchmark Overview**

The benchmark compares three ways to fill an array with zeros: using a traditional `for` loop, the `fill()` method, and the `push()` method. The goal is to determine which approach is the most efficient.

**What are we comparing?**

1. **For Loop**: A traditional `for` loop that iterates over the array length, assigning each element to zero.
2. **Array Fill**: Using the `fill()` method to fill the entire array with zeros.
3. **Push**: Using the `push()` method to add elements one by one until the desired size is reached.

**Options Compared**

* **Efficiency**: The benchmark measures the time taken to execute each approach, typically expressed as executions per second (EPS).
* **Memory Usage**: While not explicitly measured, the array sizes and memory allocation might impact performance. However, this is likely not a significant factor in JavaScript's dynamic typing.

**Pros and Cons of Each Approach**

1. **For Loop**:
	* Pros: Low overhead, easy to understand, and works well for small arrays.
	* Cons: Can be slower due to the loop control and array indexing operations.
2. **Array Fill**:
	* Pros: Fast and efficient, using native optimization.
	* Cons: May not work as expected if the desired value is not a number (e.g., string or object).
3. **Push**:
	* Pros: Can be used for arrays of varying sizes, easy to implement.
	* Cons: Generally slower than `fill()` due to the repeated array push operation.

**Other Considerations**

* **Array Allocation**: JavaScript arrays are dynamically allocated, which can lead to memory fragmentation and performance issues. However, modern engines like V8 (used in Chrome) have optimizations for this.
* **Garbage Collection**: The benchmark doesn't account for garbage collection pauses, which might impact the results.

**Library or Special JS Feature**

There's no library used in this benchmark, but keep in mind that some browsers and JavaScript engines may have specific optimization techniques for array operations. Additionally, some libraries like Lodash or underscore.js might provide optimized implementations of these methods.

**Special JS Feature (none)**

No special JavaScript features are being tested or exploited in this benchmark.

Now that we've explored the benchmark, let's look at alternative approaches:

* **Using `Array.prototype.fill()` instead of native `fill()`**: Some older browsers may not support `fill()`, so using `Array.prototype.fill()` can provide a fallback.
* **Using `Array.from()` instead of `new Array()`**: Creating an array using `Array.from()` might be more efficient than allocating a new array using `new Array()`.
* **Testing other fill methods**, such as using bitwise operations or arithmetic to fill the array.

Keep in mind that these alternatives are not part of the original benchmark, but they can provide additional insights into the trade-offs and optimizations involved.

Related benchmarks:

Array fill method vs for loop vs push (version: 0)

Array fill method vs for loop performance validation

Comparing performance of: For Loop fill vs Array Fill vs Push

Created: 2 years ago by: Guest

Jump to the latest result

For Loop fill

Array Fill

Push

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):