Benchmark: a[n] | n in a | a.length-1==n | a.at(-1)==a[n]

Tests:

a[n]
let a=[4,8,15,16,23,42],n=5; (a[n])&&(a.li=a[n])
n in a
let a=[4,8,15,16,23,42],n=5; (n in a)&&(a.li=a[n])
a.length-1==n
let a=[4,8,15,16,23,42],n=5; (a.length-1==n)&&(a.li=a[n])
a.at(-1)==a[n]
let a=[4,8,15,16,23,42],n=5; (a.at(-1)==a[n])&&(a.li=a[n])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
a[n]
n in a
a.length-1==n
a.at(-1)==a[n]

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/107.0.0.0 Safari/537.36

Browser/OS: Chrome 107 on Windows

View result in a separate tab

Test name	Executions per second
a[n]	416624896.0 Ops/sec
n in a	418515040.0 Ops/sec
a.length-1==n	420008192.0 Ops/sec
a.at(-1)==a[n]	47300388.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to help explain the JavaScript microbenchmarks on MeasureThat.net.

**Overview**

The benchmarks measure the performance of different approaches for accessing elements in an array. The tests compare four different methods:

1. `a[n]`: Direct indexing into the array using the variable `n`.
2. `(n in a) && (a[n])`: Using the `in` operator to check if `n` is a property of the array, and then accessing the element at index `n`.
3. `(a.length - 1 == n) && (a[n])`: Checking if the length of the array minus one equals `n`, and then accessing the element at index `n`.
4. `(a.at(-1) == a[n]) && (a.ni=a[n])`: Using the `at` method to access the last element of the array and compare it with the element at index `n`.

**Options Compared**

The four options are compared in terms of their performance, which is measured by the number of executions per second.

* **Direct indexing (`a[n]`)**: This approach is simple and efficient, as it directly accesses the element at the specified index.
* **Using the `in` operator (`(n in a) && (a[n])`)**: This approach checks if `n` is a property of the array, which can be slower than direct indexing. However, it's still relatively fast and widely supported.
* **Using array length and index arithmetic (`(a.length - 1 == n) && (a[n])`)**: This approach uses mathematical calculations to determine the index, which can be slower than direct indexing due to overhead from arithmetic operations.
* **Using `at` method with negative index (`(a.at(-1) == a[n]) && (a.ni=a[n])`)**: The `at` method is designed for accessing elements by their key (not index), and using it with a negative index can be slower than direct indexing or the `in` operator.

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

* **Direct indexing (`a[n]`)**:
	+ Pros: Simple, efficient, widely supported.
	+ Cons: May not work with arrays that don't have integer indices.
* **Using the `in` operator (`(n in a) && (a[n])`)**:
	+ Pros: Wide support across browsers and engines.
	+ Cons: Can be slower than direct indexing due to property lookup.
* **Using array length and index arithmetic (`(a.length - 1 == n) && (a[n])`)**:
	+ Pros: May work with arrays that don't have integer indices.
	+ Cons: Slower due to overhead from mathematical calculations.
* **Using `at` method with negative index (`(a.at(-1) == a[n]) && (a.ni=a[n])`)**:
	+ Pros: May be useful for accessing elements by their key, not index.
	+ Cons: Can be slower than direct indexing or the `in` operator due to method call overhead.

**Library and Syntax**

The tests use the following libraries and syntax:

* No external libraries are used.
* The tests use ES6 syntax (e.g., arrow functions, template literals) which is supported by most modern browsers and engines.

**Special JS Features or Syntax**

No special JavaScript features or syntax are used in these tests. However, it's worth noting that some of the approaches might not work as expected with older browsers or engines that don't support newer syntax features.

**Other Alternatives**

If you're looking for alternative approaches to accessing elements in an array, here are a few options:

* **Using `forEach` loop**: `array.forEach((element, index) => { ... });`
* **Using `map` function**: `array.map((element, index) => { ... });`
* **Using `indexOf` method**: `array.indexOf(element);`
* **Using `findIndex` method**: `array.findIndex((element, index) => { ... });`

Keep in mind that these alternatives might have different performance characteristics and may not be as efficient as the approaches tested on MeasureThat.net.

Related benchmarks:

a[n] | n in a | a.length-1==n | a.at(-1)==a[n] (version: 0)

Comparing performance of: a[n] vs n in a vs a.length-1==n vs a.at(-1)==a[n]

Created: 2 years ago by: Guest

Jump to the latest result

a[n]

n in a

a.length-1==n

a.at(-1)==a[n]

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):