Benchmark: array of objects assign (array.length) vs push (tiny array)

Script Preparation code:

var arr = [];

Tests:

new object and assign
for(let i=0; i < 10; i++) { arr[arr.length] = { i_val: i, i_val2: i+0.001 }; }
array push object
for(let i=0; i < 10; i++) { arr.push({ i_val: i, i_val2: i+0.001 }); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new object and assign
array push object

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36

Browser/OS: Chrome 105 on Linux

View result in a separate tab

Test name	Executions per second
new object and assign	74219.1 Ops/sec
array push object	77645.6 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark json and explain what's being tested.

**Benchmark Definition**

The test is designed to compare the performance of two approaches for adding objects to an array:

1. Using the `arr.length` property (assign) to dynamically set the length of the array, followed by assigning a new object to the array at that index.
2. Using the `push()` method to add a new object to the end of the array.

**Options Compared**

The two options being compared are:

* **Assign**: `arr[arr.length] = { ... }`
* **Push**: `arr.push({ ... })`

**Pros and Cons**

### Assign

Pros:

* Can be more efficient if you know the exact length of the array beforehand.
* May be faster for large arrays since it doesn't create a new element.

Cons:

* Requires knowledge of the array's current length, which might not always be available or up-to-date.
* Can lead to performance issues if the array is modified concurrently.

### Push

Pros:

* More flexible and easier to use, especially when working with dynamic data or concurrent modifications.
* Creates a new element for each addition, reducing the likelihood of off-by-one errors.

Cons:

* May be slower than assign since it creates a new element every time.
* Can lead to performance issues if the array is very large or has many push operations.

**Library Usage**

There is no explicit library usage mentioned in this benchmark. However, it's worth noting that `push()` is a built-in method of JavaScript arrays, so no external libraries are required for its usage.

**Special JS Feature/Syntax**

This benchmark does not use any special JavaScript features or syntax beyond the standard `for` loop and array operations. If you're familiar with modern JavaScript features like `let`, `const`, or arrow functions, you can easily apply those to this benchmark code without affecting the comparison.

**Alternatives**

Other alternatives for adding objects to an array could include:

* Using `splice()` to insert elements at a specific index.
* Creating a new array and assigning values using indexing (e.g., `arr[10] = { ... }`).
* Using a custom implementation, such as a linked list or vector data structure.

However, these alternatives might not be relevant to the comparison being made in this benchmark, which focuses on the performance difference between assign and push.

Related benchmarks:

array of objects assign (array.length) vs push (tiny array) (version: 1)

Adding to array of objects assign (array.length) vs push (tiny array)

Comparing performance of: new object and assign vs array push object

Created: 2 years ago by: Registered User

Jump to the latest result

new object and assign

array push object

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):