Benchmark: direct assignment vs push method

Tests:

direct assignment
const arr = []; for(let i = 0; i < 100; i++) { arr[arr.length] = i; }
push
const arr = []; for(let i = 0; i < 100; i++) { arr.push(i); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
direct assignment
push

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Android 14; Mobile; rv:134.0) Gecko/134.0 Firefox/134.0

Browser/OS: Firefox Mobile 134 on Android

View result in a separate tab

Test name	Executions per second
direct assignment	2667428.2 Ops/sec
push	1839423.5 Ops/sec

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

LLMs can make mistakes. Check important info.

**Benchmark Explanation**

The provided benchmark measures the performance difference between two approaches for initializing an array in JavaScript: direct assignment using the `[]` syntax and pushing elements to the array using the `push()` method.

**Approach Comparison**

There are two main approaches compared:

1. **Direct Assignment**: This approach uses the square bracket notation (`[]`) to initialize an empty array. The `for` loop then appends elements to this array.
2. **Push Method**: This approach uses the `push()` method to add elements to an existing array, which is initially created with the `const arr = []` syntax.

**Pros and Cons of Each Approach**

* **Direct Assignment**:
	+ Pros: Simple and concise syntax, potentially faster execution due to less overhead.
	+ Cons: May not be as efficient as using the `push()` method, especially for larger arrays.
* **Push Method**:
	+ Pros: More explicit control over array operations, potentially more efficient for larger arrays.
	+ Cons: Requires an initial array creation step, which may add overhead.

**Library and Special JS Features**

Neither of the benchmark tests uses a specific library or special JavaScript feature. The focus is on comparing the performance of two basic approach to array initialization in JavaScript.

**Other Alternatives**

If you were to write your own benchmark for this scenario, you could also consider using:

1. **Array.prototype.set()**: Introduced in ECMAScript 2015 (ES6), this method allows setting elements at a specific index in an array.
2. **Spread operator (`...`)**: Can be used to create a new array from an existing one or push elements onto it.

For example:
```javascript
const arr = [];
for (let i = 0; i < 100; i++) {
  arr.set(i, i);
}
```
or
```javascript
const arr = [1, 2, 3];
arr.push(...Array(97).fill().map((_, i) => i + 4));
```

Keep in mind that the performance differences between these approaches may be small and dependent on specific use cases.

Related benchmarks:

direct assignment vs push method (version: 0)

123

Comparing performance of: direct assignment vs push

Created: 4 years ago by: Guest

Jump to the latest result

direct assignment

push

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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