Benchmark: Array constructor vs literal performance, using push (10 items)

Tests:

Array constructor - 10 items
var n = 10; var arr = new Array(n); for (var i = 0; i < n; i++) { arr.push(i); }
Array literal (assign by index) - 10 items
var n = 10; var arr = []; for (var i = 0; i < n; i++) { arr.push(i); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array constructor - 10 items
Array literal (assign by index) - 10 items

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's dive into the explanation of the provided benchmark.

**Benchmark Overview**

The benchmark compares two approaches to create an array in JavaScript: using the `Array` constructor and using literal notation (assigning by index).

**Options Compared**

There are two options being compared:

1. **Array Constructor**: This approach involves creating a new instance of the `Array` class, passing the desired length as an argument.
```javascript
var arr = new Array(n);
```
2. **Literal Notation**: This approach involves assigning elements to the array using bracket notation and assignment (`arr[i] = i;`).
```javascript
var arr = [];
for (var i = 0; i < n; i++) {
  arr.push(i);
}
```

**Pros and Cons**

* **Array Constructor:**
	+ Pros:
		- Can be faster for large arrays, since it allows the browser to preallocate memory.
		- Can be more efficient in terms of garbage collection, as the browser doesn't need to create multiple elements.
	+ Cons:
		- Requires creating a new instance of the `Array` class, which can lead to overhead.
		- May not work well with older browsers that don't support modern array constructors.
* **Literal Notation:**
	+ Pros:
		- Is more concise and easier to read for small arrays.
		- Works consistently across all browsers.
	+ Cons:
		- Can be slower than the Array constructor, since it involves creating multiple elements on the fly.

**Library and Syntax**

Neither of these approaches relies on any external libraries or special JavaScript features. The benchmark is focused solely on comparing two basic syntaxes for array creation in JavaScript.

**Other Considerations**

When considering this benchmark, keep in mind that:

* Large arrays are more likely to benefit from the Array constructor approach.
* Small arrays may not see significant performance differences between the two approaches.
* Garbage collection and memory allocation can have a significant impact on performance, especially for large datasets.

As an alternative, you might consider adding more test cases to cover other aspects of array creation, such as:

* Using `Array.from()` or other modern array creation methods.
* Creating arrays with specific data types (e.g., objects, maps).
* Comparing the performance of different JavaScript engines or browsers.

Related benchmarks:

Array constructor vs literal performance, using push (10 items) (version: 0)

Comparing performance of: Array constructor - 10 items vs Array literal (assign by index) - 10 items

Created: 5 years ago by: Guest

Jump to the latest result

Array constructor - 10 items

Array literal (assign by index) - 10 items

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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