Benchmark: Array Initialization Types

Script Preparation code:

var times = 1000;

Tests:

Literal
var arr = []; for (var i = 0; i < times; i++) { arr[i] = 1337; }
Array()
var arr = new Array(); for (var i = 0; i < times; i++) { arr[i] = 1337; }
Array(length)
var arr = new Array(times); for (var i = 0; i < times; i++) { arr[i] = 1337; }
Literal overflow
var arr = []; for (var i = 0; i <= times; i++) { arr[i] = 1337; }
Array() overflow
var arr = new Array(); for (var i = 0; i <= times; i++) { arr[i] = 1337; }
Array(length) overflow
var arr = new Array(times); for (var i = 0; i <= times; i++) { arr[i] = 1337; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Literal
Array()
Array(length)
Literal overflow
Array() overflow
Array(length) overflow

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the explanation of what is being tested on MeasureThat.net.

The benchmark compares three ways to initialize an empty array in JavaScript:

1. **Literal** (`var arr = [];`): This method creates an empty array using square brackets `[]`. The test case also includes a loop that populates the array with a large number of elements (1000 times).
2. **Array()`**: This method creates an empty array by calling the `Array()` constructor without any arguments.
3. **Array(length)** (`var arr = new Array(times);`): This method creates an empty array with a specified length, which is set to 1000 in this case.

The benchmark also tests for overflow cases:

* **Literal overflow** (`for (var i = 0; i <= times; i++) {\r\n\tarr[i] = 1337;\r\n}`): This test case tries to populate the array with a large number of elements, but exceeds the maximum allowed index.
* **Array() overflow** (`for (var i = 0; i <= times; i++) {\r\n\tarr[i] = 1337;\r\n}`): Similar to the literal overflow, but uses the `Array()` constructor.
* **Array(length) overflow** (`for (var i = 0; i <= times; i++) {\r\n\tarr[i] = 1337;\r\n}`): Again, tries to populate an array with a large number of elements using the `Array(length)` method.

Let's discuss the pros and cons of each approach:

* **Literal**: This method is simple and easy to understand. However, it may not be as efficient as the other two methods since it doesn't provide any information about the size of the array.
* **Array()**: This method is slightly more efficient than the literal method, but still has a performance overhead due to the constructor call.
* **Array(length)**: This method is generally the most efficient way to initialize an empty array, as it allows the browser to allocate memory for the specified length. However, if the length is too large, it may lead to memory allocation issues.

Other considerations:

* The benchmark uses a fixed number of executions (1000) and a constant value for each test case. This might not accurately reflect real-world scenarios.
* The tests do not account for other factors that could affect performance, such as browser version, platform, or hardware.

As for special JavaScript features or syntax, none are explicitly mentioned in this benchmark.

Now, let's talk about alternative approaches:

* **Using `Array.from()`**: This method creates an empty array using the `from` keyword. It is generally faster and more efficient than the other methods.
* **Using a constructor with no arguments**: Some browsers, like WebKit, support using a constructor with no arguments to create an empty array. However, this method is not widely supported.
* **Using a typed array**: Typed arrays, such as `Int32Array` or `Float64Array`, can be used to create an empty array with a specified type and length.

Keep in mind that these alternative approaches might have different performance characteristics and are not necessarily better than the original methods.

Latest run results:

Run details: (Test run date: 8 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:47.0) Gecko/20100101 Firefox/47.0

Browser/OS: Firefox 47 on Mac OS X 10.11

View result in a separate tab

Test name	Executions per second
Literal	91274.2 Ops/sec
Array()	97034.9 Ops/sec
Array(length)	124627.3 Ops/sec
Literal overflow	92695.4 Ops/sec
Array() overflow	93324.9 Ops/sec
Array(length) overflow	102888.4 Ops/sec

Related benchmarks:

Array Initialization Types (version: 0)

[] vs Array() vs Array(length)

Comparing performance of: Literal vs Array() vs Array(length) vs Literal overflow vs Array() overflow vs Array(length) overflow

Created: 8 years ago by: Registered User

Jump to the latest result

Literal

Array()

Array(length)

Literal overflow

Array() overflow

Array(length) overflow

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):