Benchmark: Add new element to array: push vs array[array.length]

Tests:

Push
var params = [ "hello", true, 7 ]; params.push('new');
array[array.length]
var params = [ "hello", true, 7 ]; params[params.length] = 'new';

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Push
array[array.length]

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 130 on Android

View result in a separate tab

Test name	Executions per second
Push	52466484.0 Ops/sec
array[array.length]	55667176.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases to understand what is being tested.

**Benchmark Definition:**

The website, MeasureThat.net, allows users to create and run JavaScript microbenchmarks. The current benchmark definition represents two different approaches for adding a new element to an array:

* `push`: Using the `push()` method to add a new element at the end of the array.
* `array[array.length]`: Directly accessing the last index of the array using bracket notation (`[]`) and assigning a new value.

**Options Compared:**

The two options being compared are:

1. `push()`: This method appends a new element to the end of the array, creating a new reference.
2. `array[array.length]`: This approach directly accesses the last index of the array, creating a new reference by indexing into the existing array.

**Pros and Cons:**

* `push()`:
	+ Pros: Easy to read and write, doesn't require knowing the length of the array.
	+ Cons: Creates a new reference for the new element, potentially causing performance issues if used in loops or large datasets.
* `array[array.length]`:
	+ Pros: Directly accesses the last index without creating a new reference, potentially faster.
	+ Cons: Requires knowing the length of the array and using bracket notation, which can be less readable.

**Library and Special JS Feature/ Syntax:**

Neither of the benchmarked code snippets uses any external libraries or special JavaScript features/syntax. The `push()` method is a standard Array method in JavaScript, while the `array[array.length]` approach relies on bracket notation and indexing into arrays.

**Other Alternatives:**

Some other ways to add an element to an array include:

* Using the spread operator (`...`) to create a new array with the existing elements plus the new one: `[...params, 'new']`.
* Using the `concat()` method to concatenate the existing array with a new array containing the new element: `params.concat(['new'])`.
* Using `Set` data structure instead of arrays.

These alternatives may have different performance characteristics and use cases compared to the `push()` and `array[array.length]` approaches.

**Benchmark Preparation Code and HTML Preparation Code:**

The provided benchmark definition does not include any script preparation code or HTML preparation code. This means that the test cases are designed to be run in a standard web browser environment, with no external dependencies or setup required for the tests.

Related benchmarks:

Add new element to array: push vs array[array.length] (version: 0)

Add new element to array: push vs array[array.length]

Comparing performance of: Push vs array[array.length]

Created: 2 years ago by: Guest

Jump to the latest result

Push

array[array.length]

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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