Benchmark: Array push vs - MeasureThat.net

Tests:

a
const a = []; for( let i=0; i<100000;i++ ) a.push( Math.random() );
b
const a = []; for( let i=0; i<100000;i++ ) a[ a.length] = Math.random();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
a
b

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 2 days ago):

LLMs can make mistakes. Check important info.

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

**What is being tested?**

The provided JSON represents two individual test cases for a JavaScript microbenchmark: `Array push vs`. The goal of this benchmark is to compare the performance of two different ways of pushing elements onto an array in JavaScript.

**Options being compared**

There are two options being compared:

1. **`a.push(Math.random())`**: This option uses the `push()` method to add a new element to the end of the array.
2. **`a[a.length] = Math.random()`**: This option uses the syntax `a[a.length] = ...` to access and assign a value to the last index of the array.

**Pros and Cons of each approach**

1. **`a.push(Math.random())`**:
	* Pros: Easy to read and write, concise, and efficient in most cases.
	* Cons: May have performance overhead due to the `push()` method's internal implementation.
2. **`a[a.length] = Math.random()`**:
	* Pros: Direct access to the last index of the array can be faster for large arrays or when working with a fixed-size array.
	* Cons: Less readable and more verbose, may require careful handling of edge cases (e.g., `undefined` or `null` values).

**Other considerations**

* The use of `Math.random()` to generate random numbers introduces additional overhead due to the cost of generating random numbers.
* Both options assume that the array is not yet initialized; if the array needs to be preinitialized, the performance difference may be less pronounced.

**Library usage**

None of the provided code snippets use any external libraries.

**Special JS features or syntax**

There are no special JavaScript features or syntax used in these benchmark tests. They only rely on standard JavaScript syntax and built-in functions.

**Alternatives**

If you need to compare other aspects of array manipulation, such as:

* **`a[0] = ...`**: Accessing the first element of an array.
* **`a.indexOf(...)`**: Finding a specific value in an array.
* **`Array.prototype.forEach()`**: Iterating over an array using a callback function.

You can create additional test cases to compare these different approaches.

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/96.0.4664.110 Safari/537.36

Browser/OS: Chrome 96 on Windows

View result in a separate tab

Test name	Executions per second
a	50.5 Ops/sec
b	51.8 Ops/sec

Related benchmarks:

Array push vs (version: 0)

Comparing performance of: a vs b

Created: 2 years ago by: Guest

Jump to the latest result

a

b

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Sumamry (model llama3.2:3b, generated 2 days ago):